Neuraminidase-enhanced attachment of Bacteroides intermedius to human erythrocytes and buccal epithelial cells.

Bacteroides intermedius strains strongly agglutinated only neuraminidase-treated erythrocytes. The neuraminidase-dependent hemagglutinating activity of B. intermedius was abolished by heating or treating with protease. The adherence of these microorganisms to human buccal epithelial cells was enhanced by neuraminidase pretreatment of the cells (P less than 0.01).     

Slow reacting substance as a preformed mediator from human lung.

Homogenates from human lung contained a preformed slow reacting substance (pSRS). The pattern of contraction on the guinea-pig ileum by pSRS was indistinguishable from that of SRS-A. The activity of pSRS could not be attributed to the presence of K+, Na+, Ca2+ and Mg2+ ions, or any prostaglandin including PGF2 or its 15-oxo derivative. As with SRS-A, pSRS could be absorbed onto Amberlite XAD-2 and silicic acid. Both were eluted from the former with 80 per cent ethanol and from the latter with a mixture of ethanol, ammonia and water. Both pSRS and SRS-A were resistant to the action of NaOH whereas their activities were destroyed by boiling in HCl. Arylsulphatase II B destroyed the activities of both pSRS and SRS-A. An antagonist of SRS-A, FPL55712, inhibited the action of pSRS at comparable concentrations to that of SRS-A. These experiments suggest that pSRS and SRS-A are identical. Thus SRS joins histamine and ECF-A as a preformed mediator. Although SRS was present in a preformed state the amount of material extractable was more than doubled by the anaphylactic reaction. The extraction of slow reacting substance from human lung without apparent requirement for antigen or antibody points to a possible role of this mediator in inflammatory reactions evoked by mechanisms independent of IgE and other tissue-sensitizing antibodies.     

Pili of a Vibrio parahaemolyticus strain as a possible colonization factor.

Pili of Vibrio parahaemolyticus were purified from a Kanagawa phenomenon-positive strain (Ha7) that belongs to serogroup O2:K3 and is adhesive to rabbit intestine. The organisms treated with the Fab fraction of antipilus antibody failed to adhere to the intestine. Purified pili had the ability to adhere to the intestine, but the pretreatment of the intestine with purified pili did not allow adherence of the organisms to the intestine. These results suggest that pili of this V. parahaemolyticus strain play an important role in colonization.     

Attachment and ingestion of gonococci human neutrophils.

Previous studies have indirectly shown that type 1 gonococci are more resistant to phagocytosis by human neutrophils (PMN) than type 3 gonococci. Using phase contrast, fluorescent, and light microscopy, we directly quantitated PMN-gonococcal interaction, with emphasis on separating ingestion from attachment. PMN monolayers were incubated on slides with type 1 or type 3 gonococcal fluorescent antibody (FA). After methanol fixation, the FA-stained gonococci associated with PMN were cointed. Since the live PMN excludes FA, the FA-stained gonococci represent only extracellular gonococci. Methylene blue was then added to the smae slide to stain both ingested and surface attached gonococci. Using these methods, intracellular and extracellular cell-associated gonococci were quantitated under varying conditions. The numbers of methylene blue-stained cell-associated gonococci that were ingested were: with normal serum, 3.7 plus or minus 4.1 per cent for type 1 and 56.2 plus or minus 3.7 percent for type 3 (P smaller than 0.001); with heat-inactivated serum, 1.0 plus or minus 3.0 per cent for type 1 and 52.6 plus or minus 3.7 per cent for type 3 (P smaller than 0.001); with higher-titer anti-gonococcal antibody serum, 4.8 plus or minus 4.3 percent for type 1 and 64.0 plus or minus 1.6 per cent for type 3 (P smaller than 0.001). Thus, most type 3 organisms were ingested, but most type 1 gonococci were bound on the PMN surface.     

Location of brown recluse venom attachment sites on human erythrocytes by the firritin-labeled antibody technique.

Brown recluse spider (loxosceles reclusa) venom has been demonstrated by a ferritin-labeled antibody technique to attach to human erythrocyte cell membranes. The number of individual attachment sites per cell is proportional to the concentration of the venom used to sensitize the erythrocytes. Structural changes in the red cell membrane are associated with the venom attachment. These sites may be related to the red cell hemolysis which sometimes occurs in the human as a result of the spider bite.     

Adult attachment as mediator between recollections of childhood and satisfaction with life

In accordance with attachment theory, the present study investigates whether internal working models of attachment mediated the association between childhood memories and satisfaction about life in adulthood. A convenient sample of 437 participants completed questionnaires assessing a broad range of childhood memories, working models of attachment and life satisfaction. After controlling for demographics, relational status and living condition, Baron and Kenny's mediation criteria were met for the association between memories about childhood, adult attachment and life satisfaction. That is, family warmth and harmony and parental support were associated with attachment security while parental rejection and adverse childhood events (e.g., abuse, parental psychopathology) were associated with an insecure attachment style. More securely attached individuals were in turn more satisfied about their current life than insecurely attached individuals. Sobel test confirmed these findings. These finding are in accordance with attachment theory and highlight the importance of this theory for understanding how early childhood experiences may impact adult life. Copyright © 2008 John Wiley & Sons, Ltd.     

The attachment of encephalomyocarditis virus to erythrocytes from several animal species.

Attachment of encephalomyocarditis (EMC) virus to many species of erythrocytes requires sialic acid residues on the cell surface. Apart from bovine erythrocytes which are not agglutinated by EMC virus, different species of erythrocytes require different numbers of virions for hemagglutination. These differences are apparently not related to the sialic acid content of the erythrocytes or to the rate at which they bind virus but may be related to the total number of viral receptors available per cell.     

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.     

SECA, a new mediator of the human eosinophil response.

Spontaneous eosinophilic chemotactic activity (SECA) present in human sera can mediate the directed movement of normal human eosinophils. Our data utilize normal peripheral blood eosinophils obtained from subjects with 500 eosinophils/m3 or less. SECA is defined as that chemotactic activity for eosinophils present in serum that has been heat-inactivated immediately after collection. It was demonstrated in patients with severe chronic eczema with eosinophilia (20 to 30%); mixed collagen vascular disease with vasculitis; clinical serum sickness; acute glomerulonephritis, and chronic membranoproliferative glomerulonephritis. Control sera were obtained from normal, healthy individuals. The data indicated: (1) that SECA in patient sera was significantly higher than in control sera; (2) when activated by endotoxin, no additional chemotactic activity was generated from patient sera over that spontaneously present--by contrast, addition of endotoxin to control sera did result in increased chemotactic activity; (3) sera from patients with extrinsic bronchial asthma had no SECA.     

Adherence of Ureaplasma urealyticum to human erythrocytes.

Ureaplasma urealyticum (four serotypes and two clinical isolates) were metabolically labeled with radioactive methionine to a high specific activity. Labeling allowed the study of the mechanism of adherence to human erythrocytes. The adherence mechanism was complex and partially mediated by proteinaceous surface components. The binding sites on the erythrocytes were partially sensitive to neuraminidase treatment, and adherence was inhibited by glycophorin and dextran sulfate, indicating recognition of sialyl residues and sulfated compounds.     

Permeability of individual human erythrocytes to thiourea.

The osmotic swelling to haemolysis of individual red blood cells by isosmotic thiourea has been studied using microcine photography. 2. Crenation occurs immediately upon addition of isosmotic thiourea. The cell becomes a crenated sphere without volume decrease. 3. Subsequently, the cell volume increases linearly with time with maximum swelling occurring at about 102 sec which is 81% of the total haemolysis time. 4. At maximum swelling, the cell volume is 92% greater than the initial cell volume. This volume increase is about double that measured with other permeating substances. 5. The much larger maximum volume implies that thiourea increases the area of the cell membrane. This increase varies from 0 to 75% for individual cells, with a mean of 22%. 6. Membrane expansion varies inversely as the initial cell membrane area and cell volume (r=0-790). 7. Using the increased surface area, increased maximum volume and the swelling time, the mean permeability is calculated to be 5-52 X 10(-7) cm/sec (S.D. of mean=+/-1-19 X 10(-7) cm/sec). The distribution of permeabilities represents a normal distribution. 8. The pre-lytic potassium loss ranged from 0 to 36% with a mean value of 16-5%. This is consistent with values reported in the literature for slow haemolysis. As with other permeants the distribution is skewed towards lower values. 9. Membrane permeability of individual cells varies with the amount of membrane expansion observed. Coefficient of correlation between permeability and expansion index is 0-674. 10. There is no correlation between permeability and the reciprocal of the haemolysis time (r=-0-035). The correlation between permeability and the reciprocal of the swelling time is also poor (r=0-303), probably owing to the variability in membrane expansion by thiourea in individual cells. 11. As has been shown previously for faster permeants, the permeability coefficient cannot be calculated from the haemolysis time. Because thiourea alters the membrane area and the haemolytic volume, the coefficient cannot be calculated from the swelling time unless the changes in the membrane area are also taken into account.     

Glycoprotein recognition mediates attachment of Plasmodium chabaudi to mouse erythrocytes

The interaction between Plasmodium falciparum merozoites and human erythrocytes is mediated by specific parasite proteins and sialoglycoproteins (SGPs) on the surface of the host cell. To investigate whether a similar mechanism functions in rodent malaria, a series of experiments was performed to identify the proteins involved in the interaction of Plasmodium chabaudi parasites and mouse erythrocytes. Labeled parasite proteins incubated with purified mouse SGP bound specifically to glycoprotein 2.1. Two parasite proteins (72 and 126 kilodaltons [kDa]) were coprecipitated with antibody directed to mouse erythrocyte membrane proteins. The lower band (72 kDa) as well as a band of 105 kDa were also observed to bind to N-acetyl-D-galactosamine affinity columns, suggesting a carbohydrate component in the binding of these parasites to erythrocytes. These experiments indicate that P. chabaudi possesses specific proteins which recognized SGP on the surface of murine erythrocytes in a manner similar to that of the merozoites of P. falciparum. Thus P. chabaudi in mice may provide an in vivo model of the human parasite for testing ways to inhibit merozoite recognition and invasion of host cells.     

Fibronectin-enhanced attachment of gelatin-coated erythrocytes to isolated hepatic Kupffer cells

The phagocytic process is a combination of a sequence of events which includes a recognition attachment phase and a subsequent internalization phase. The present study was designed to investigate the effect of plasma fibronectin on the attachment and ingestion of gelatinized sheep erythrocytes to isolated rat Kupffer cells in a monolayer assay. Kupffer cells were isolated by sequential collagenase-pronase digestion followed by metrizamide density gradient centrifugation and subsequent adherence to plastic. Classification as Kupffer cells was confirmed by the presence of functional Fc receptors, a positive peroxidase reaction, and phagocytic activity. Purified plasma fibronectin as well as rat serum containing fibronectin promoted attachment of gelatinized fixed sheep erythrocytes to Kupffer cells in a dose-dependent manner, whereas fibronectin-deficient serum did not. Heparin did not enhance the fibronectin-mediated attachment or ingestion of gelatinized sheep erythrocytes at lower particle doses, whereas at higher particle doses heparin augmented the response. These results indicate that fibronectin can enhance the binding and ingestion of foreign gelatin-coated particulates by Kupffer cells.     

Aminoglycosides and polymyxin B as inhibitors of antigen attachment to erythrocytes for agglutination by Salmonella antibodies

Previous investigations indicate that polymyxin B inhibits attachment of lipopolysaccharides (O antigens) to erythrocytes and subsequent hemagglutination by the corresponding bacterial antibodies. In this study the effect of this antibiotic was compared to that of the aminoglycosides gentamicin, tobramycin, and amikacin. Using both crude O antigens and highly purified lipopolysaccharides, polymyxin B was at least 100 times more effective than the aminoglycosides. Amikacin proved to be less effective than gentamicin and tobramycin.     

Mast cell tryptase as a mediator of hyperresponsiveness in human isolated bronchi

BACKGROUND: Although the role of mediators and cytokines produced by mast cells is well established in asthmatic bronchial inflammation, the contribution of mast cell-derived proteases to the development of hyperresponsiveness remains unclear. There have been reports indicating that tryptase alters the mechanical activity of animal airway smooth muscle or spontaneously sensitized human isolated airways. OBJECTIVE: The aim of this study was to analyse the effect of purified mast cell tryptase on non-sensitized human isolated bronchi. METHODS: Both central and peripheral bronchi, dissected from lung specimens obtained at thoracotomy, were studied in terms of both mechanical activity i.e. isometric contraction in response to a variety of agonists and distribution of inflammatory cells i.e. immunohistochemistry. RESULTS: In both proximal and distal bronchi, the reactivity to histamine was significantly increased by a previous incubation in the presence of 1 microg/mL of tryptase (increase in maximal force, DeltaFmax was 12.1 +/- 3.8%, and 8.8 +/- 3.1%, respectively). This effect of tryptase on histamine-induced contraction was completely abrogated in the presence of the protease inhibitor benzamidine (100 micromol/L). Histological examination of specimens exposed to tryptase demonstrated an increase in mast cell number within the subepithelial tissue whereas mast cell numbers in the epithelial layer concomittently decreased. CONCLUSION: These results indicate that human mast cell tryptase alters the contractile response of non-sensitized human isolated bronchi and that this alteration is accompanied by a change in the mast cell distribution within the airway wall.     

Escherichia coli pili as possible mediators of attachment to human urinary tract epithelial cells.

Presence of pili of fimbriae on Escherichia coli bacteria isolated from the urine of patients with urinary tract infection was related to the ability of the bacteria to attach to human uroepithelial cells. Piliated E. coli strains agglutinated guinea pig erythrocytes. D-Mannose and alpha-methyl-D-mannopyranoside inhibited this agglutination with all but one of the 12 strains tested. D-Mannose, D-galactose, alpha-methyl-D-mannopyranoside, and L-fucose did not afect attachment of piliated strains to uroepithelial cells. Heating as well as washing of piliated strains caused a parallel decrease of piliation and adhesive ability. Growth in glucose-enriched medium increased capsule formation but decreased piliation and adhesion. Capsulated strains retained their adhesive ability provided that pili extended outside the capsule.     

Adhesion of Entamoeba histolytica trophozoites to human erythrocytes.

To understand the mechanism of Entamoeba histolytica adhesion, we characterized the binding of trophozoites to human erythrocytes (RBC) in suspension by measuring the kinetics of amoeba-RBC complex formation. Adhesion was very efficient, since most of the amoebae were complexed with RBC after only 5 min at 37 degrees C in mixtures containing 10(4) amoebae and 10(6) RBC per ml; the adhesion rate depended on amoeba and RBC concentrations, but not on the A, B, and O human blood groups, and was maximal at 37 degrees C and pH 7.3 in the presence of 4 mM Ca2+ and 1 mM Mg2+. Adhesion was prevented if trophozoites were fixed with glutaraldehyde, but only decreased slightly if RBC were previously fixed; it decreased in the absence of glucose and was inhibited as a function of the concentration of cytochalasin B and of the metabolic inhibitors bathophenanthroline and 8-hydroxyquinoline. From these results we conclude that E. histolytica adhesion is an active process that depends on the amoebal cytoskeleton and metabolic energy and on the mobility of both amoebal and RBC surface ligands.     

Failure of the fluorescent antibody reaction to identify penicillinase-producing gonococci.

The fluorescent antibody test is now widely used to confirm the identity of Neisseria gonorrhoeae but may fail to identify penicillinase-producing strains (PPNG). This problem arises when conjugates are used that incorporate only gonococci that are not penicillinase-producers. We have shown that conjugates prepared from mixtures of PPNG and non-penicillinase producing gonococci give good fluorescent reactions. This difference in the reactions of PPNG strains is clearly related to their penicillinase-producing abilities, further study of the antigenic relation between penicillinase production and the antigenic structure of N gonorrhoeae is evidently required.