Anti-biofilm and anti-adherence properties of novel cyclic dipeptides against oral pathogens

Microorganisms embedded in a biofilm are significantly more resistant to antimicrobial agents and the defences of the human immune system, than their planktonic counterpart. Consequently, compounds that can inhibit biofilm formation are of great interest for novel therapeutics. In this study, a screening approach was used to identify novel cyclic dipeptides that have anti-biofilm activity against oral pathogens. Five new active compounds were identified that prevent biofilm formation by the cariogenic bacterium Streptococcus mutans and the pathogenic fungus Candida albicans. These compounds also inhibit the adherence of microorganisms to a hydroxylapatite surface. Further investigations were conducted on these compounds to establish the structure–activity relationship, and it was deduced that the common cleft pattern is required for these molecules to act effectively against biofilms.     

Localization of neutrophil adherence-inhibiting factor in guinea pig platelets

The effect of constituents of guinea pig platelets on neutrophil adherence was examined. The platelet sonicate supernatant contained adherence-inhibiting activity which strongly inhibited neutrophil adherence to glass. When the platelet sonicate supernatant was treated with neuraminidase or trypsin, the adherence-inhibiting activity was significantly inhibited, suggesting that the adherence-inhibiting factor (AIF) is a glycoprotein. The subcellular fractionation experiments indicated that the AIF activity was present at about 40% in both the cytosol and granule fractions. From the Sephadex G-200 gel filtration analysis, AIF of cytosol fraction and granule fraction proved to be different molecules, with molecular masses of about 230 and 12 kDa, respectively. When platelets were stimulated with thrombin, about 20% of total AIF was released extracellularly without the release of the cytoplasmic enzyme lactate dehydrogenase. These results suggest the possibility that a biologically active substance, AIF, is released from platelets in response to stimuli and regulates neutrophil functions through interference with neutrophil adherence.     

Comparative studies on the adhesiveness of granulocytes of guinea pig and man

Summary The high affinity of granulocytes of guinea pig and man to glass surfaces is modified by serum. Native serum contains both an adherence-promoting activity, which is related to complement, and components which reduce the adhesiveness of granulocytes. These components are stable at 56°C for 30 min and are tightly bound to the glass surface. -Lipoproteins are candidates for this adherence reducing ability of serum. Adherence promotion by native serum is mediated by coating the glass surface with C3b/C3bi. Human granulocytes from the peripheral blood adhered to glass surfaces coated by native human or guinea pig serum with C3b/C3bi to almost the same extent as in the presence of native serum, but on guinea pig granulocytes elicited in the peritoneal cavity, a cell surface metalloproteinase degraded the C3b/C3bi, thus reducing the adhesiveness of these cells. This proteinase was inhibited by MgEDTA, DTT, and 1,10-phenanthroline, whereby the high adhesiveness of granulocytes was restored to C3b/C3bi-coated glass.Abbreviations BA benzamidine hydrochloride - BTS Bacillus thuringiensis subtoxicus - DTT dithiothreitol - EAC -amino-caproic acid - gp guinea pig - LDL low density lipoproteins - SEM scanning electron microscopy     

Hemagglutinating and adherence properties of Staphylococcus saprophyticus: epidemiology and virulence in experimental urinary tract infection of rats

Abstract We studied hemagglutinating and adherence properties in Staphylococcus saprophyticus isolates originating from symptomatic urinary tract infections. 12/13 (92%) of strains adhered to Hep cells and 11/13 (85%) were able to agglutinate sheep erythrocytes. Adherence properties differed markedly between strains ( P < 0.0001. Two strains, one hemagglutinating and adherent and one negative for both properties were chosen for experimental urinary tract infections. Results indicate that presence of the hemagglutinin favours colonization of kidney tissue.     

Inhibition of Bordetella pertussis filamentous hemagglutinin-mediated cell adherence with monoclonal antibodies

Abstract Filamentous hemagglutinin (FHA), a 220-kDa protein located on the surface of Bordetella pertussis , is one of the major cell adhesins of this bacterium. We have produced three hybridoma cell lines that express monoclonal antibodies (mAbs) against FHA: X3C, X3E and X4B. The anti-FHA mAbs X3C and X3E reacted with 220-kDa FHA protein bands on Western blots. The mAb X4B, which reacted with FHA in ELISA, did not bind to FHA in a Western blot assay. All three mAbs seemed to be directed to the same epitope or to epitopes in close proximity as suggested by competition ELISAs. All three mAbs were able to inhibit the adherence of Chinese hamster ovary cells to purified FHA, and they could also inhibit the FHA-mediated agglutination of goose red blood cells. The attachment of B. pertussis to epithelial cell monolayers was inhibited by the mAb X3C. These antibodies are very useful probes to identify the presence of FHA in bordetellae species and in clinical reagents such as pertussis vaccines, and to characterize the functional domains of this important bacterial adhesin.     

次最低抑菌浓度抗生素对双歧杆菌粘附的影响

本文观察了八种抗生素在次最低抑菌浓度（Ｓｕｂ－ＭＩＣ）下对双歧杆菌和体外培养肠上皮细胞间粘附的影响。结果表明,次最低抑菌浓度的抗生素均能显著地抑制双歧杆菌的粘附,青霉素和万古霉素对双歧杆菌粘附的抑制有剂量及时间效应。提示抗生素抑制双歧杆菌的粘附可能是其引起肠道微生态失衡的一条重要途径。     

The effect of temperature on eicosane substrate uptake modes by a marine bacterium Pseudomonas nautica strain 617: relationship with the biochemical content of cells and supernatants

Three hydrocarbon uptake modes (adherence, emulsification and solubilization) were identified and quantified in cells and supernatants of a mesophilic marine bacterium Pseudomonas nautica strain 617 grown on eicosane. The adherence capacity was related to the enrichment of cells with wax esters and glycolipids. The emulsifying activity was related to the presence of extracellular biosurfactants composed of proteins, carbohydrates and lipids (35:63:2). The intensity of substrate uptake modes was sensitive to temperatures currently found in the original environment of P. nautica (16°C, 20°C and 32°C). When temperature decreased, a significant increase in adherence and emulsifying activity was observed in relation to biochemical changes, whereas solubilizing activity decreased. The marine bacterium was able to degrade 53–59% eicosane at the end of exponential growth after 13, 5 and 3 days incubation at 16°C, 20°C and 32°C respectively.     

Biomass yields of Chlorella from iron (Y x/Fe) in iron-limited batch cultures

The maximum biomass in iron-limited photosynthetic batch cultures of chlorella increased as the logarithm of the iron concentration. The growth yield from iron (Y _x/Fe) showed a marked inverse relation to the specific growth rate. The maximum biomass yield, g dry biomass/g iron consumed, was 7.5x10³ with specific growth rate 0.108 h^-1; the minimum was 0.79×10³ with specific growth rate 0.145 h^-1. The maximum specific growth rate in the exponential phase of Fe limited cultures varied as the initial Fe concentration. Fe-limited growth made the cells adhere to a glass surface.Abbreviation O.D. optical density     

CR1-mediated ATP Release by Human Red Blood Cells Promotes CR1 Clustering and Modulates the Immune Transfer Process

Humans and other higher primates are unique among mammals in using complement receptor 1 (CR1, CD35) on red blood cells (RBC) to ligate complement-tagged inflammatory particles (immune complexes, apoptotic/necrotic debris, and microbes) in the circulation for quiet transport to the sinusoids of spleen and liver where resident macrophages remove the particles, but allow the RBC to return unharmed to the circulation. This process is called immune-adherence clearance. In this study we found using luminometric- and fluorescence-based methods that ligation of CR1 on human RBC promotes ATP release. Our data show that CR1-mediated ATP release does not depend on Ca²⁺ or enzymes previously shown to mediate an increase in membrane deformability promoted by CR1 ligation. Furthermore, ATP release following CR1 ligation increases the mobility of the lipid fraction of RBC membranes, which in turn facilitates CR1 clustering, and thereby enhances the binding avidity of complement-opsonized particles to the RBC CR1. Finally, we have found that RBC-derived ATP has a stimulatory effect on phagocytosis of immune-adherent immune complexes.     

Adherence and autoaggregation phenotypes of a Burkholderia cenocepacia cable pilus mutant

Cable pili are unique peritrichous adherence organelles expressed by certain strains of the opportunistic human pathogen Burkholderia cenocepacia. Cable pili have been proposed to facilitate binding to human epithelial cells and mucin, and may play a role in the ability of B. cenocepacia to colonise the respiratory tract of compromised hosts. In this study, a genetic approach was undertaken to assess the role of cable pili in mediating adherence as well as bacterial cell-cell interactions. The cblA gene, encoding the major pilin subunit, was insertionally inactivated, and the resulting mutant was shown to be blocked in CblA expression and in cable pilus morphogenesis. Although non-piliated, the cblA mutant was not defective in adherence to either porcine mucin or to cultured A549 human respiratory epithelial cells. Microscopic and flow cytometric analyses of B. cenocepacia cultures revealed that cable pilus expression facilitated the formation of diffuse cell networks, whereas disruption of cable pilus biogenesis enhanced autoaggregation and the formation of compact cell aggregates. Autoaggregation was observed both in culture and during B. cenocepacia infection of A549 epithelial cell monolayers. These findings indicate that cable pilus expression plays an important role in mediating B. cenocepacia cell-cell interactions, and that both cable pilus-dependent and cable pilus-independent mechanisms may contribute to B. cenocepacia adherence to cellular and acellular surfaces.