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Query: UMLS:C0085631 (agitation)
 12,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inhibition of flocculation by sugars was studied in 41 strains of Saccharomyces cerevisiae. Two distinct groupings were found. The first type, including all strains containing FLO 1, FLO 4, FLO 5, FLO 8 and TUP 1, were partially inhibited by mannose only. The second type (NewFLO) were completely inhibited by mannose, maltose, glucose and sucrose. Sugar inhibitions were reversible and were exacerbated by increased agitation. NewFLO strains were more sensitive to inhibition by inorganic salts than the FLO 1 type strains. This inhibition is probably chaotropic in nature. Most FLO 1 type strains are constitutive, expressing flocculation throughout growth, whereas, NewFLO strains are completely repressed by the presence of excess ammonium ions. It is proposed that this indicates two entirely distinct mechanisms of flocculation, probably involving a mannose-specific lectin in the FLO 1 type and a broad specificity lectin in the NewFLO type.
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PMID:Evidence for two mechanisms of flocculation in Saccharomyces cerevisiae. 266 72

Most endothelial cells (EC) in the body belong to the microvasculature. Isolation and subsequent culture of these microvessel EC contributes greatly to our understanding of the heterogeneity and vascular specificity that exist between one organ site and another. However, a major obstacle is the overgrowth of contaminating cells (fibroblasts, pericytes, smooth-muscle cells) in cultures. Since 1990 the use of magnetic beads in combination with either a lectin, Ulex europaeus agglutinin-1 (UEA-1), or a monoclonal antibody has represented a powerful tool for the isolation/purification of microvessel EC. In the former case, operative conditions remain to be optimized to obtain pure cultures of EC. We have performed studies to optimize conditions of use for magnetic beads coated with UEA-1. Incubating beads with cells, the influences are studied of time, temperature, cell concentration, and number of beads per target cell for two cell types, human umbilical vein EC (HUVEC) and skin fibroblasts (HSF), either isolated or mixed. The effect of the last parameter was also checked on the behavior of cells undergoing proliferation after isolation. Results, expressed as isolation efficiency (from 40% to 90%) allowed us to select a 15-min incubation time at 4 degrees C with rotary agitation, an optimal concentration of 4 x 10(5) cells/ml, and an optimal cell:bead ratio of 1:3. From a mixed cell population and in these conditions, even very low HUVEC:HSF proportions of 2.5:97.5 allowed us to obtain a pure HUVEC population in subsequent culture.
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PMID:Optimization of use of UEA-1 magnetic beads for endothelial cell isolation. 903 8

The choice of host cell receptor and the mechanism of binding (opsonic versus nonopsonic) may influence the intracellular fate of Mycobacterium tuberculosis. We have identified two substrains of M. tuberculosis H37Rv, designated H37Rv-CC and -HH, that differed in their modes of binding to complement receptor type 3 (CR3) expressed in transfected Chinese hamster ovary (CHO-Mac-1) cells: H37Rv-CC bound nonopsonically, whereas H37Rv-HH bound only after opsonization in fresh serum. H37Rv-CC also bound nonopsonically to untransfected CHO cells, whereas H37Rv-HH binding was enhanced by serum and was mediated by the 1D1 antigen, a bacterial adhesin previously identified as a polar phosphatidylinositol mannoside. H37Rv-CC and -HH had identical IS6110 DNA fingerprint patterns. Of five M. tuberculosis clinical isolates examined, four displayed the same binding phenotype as H37Rv-CC, as did the Erdman strain, whereas one isolate, as well as Mycobacterium smegmatis, behaved like H37Rv-HH. Nonopsonic binding of H37Rv-CC to CHO cell-expressed CR3 was apparently to the beta-glucan lectin site, as it was cation independent and inhibited by laminarin (seaweed beta-glucan) and N-acetylglucosamine; laminarin also inhibited the binding of H37Rv-CC to monocyte-derived macrophages. Further, binding of H37Rv-CC to CHO-Mac-1 cells was inhibited by prior agitation of bacteria with glass beads (which strips outer capsular polysaccharides) and by preincubation with amyloglucosidase, as well as by the presence of capsular D-glucan and D-mannan from M. tuberculosis Erdman, but not by Erdman D-arabino-D-mannan, yeast mannan, or capsular components from H37Rv-HH. Analysis of capsular carbohydrates revealed that H37Rv-CC expressed 5-fold more glucose and 2.5-fold more arabinose and mannose than H37Rv-HH. Flow cytometric detection of surface epitopes indicated that H37Rv-CC displayed twofold less surface-exposed phosphatidylinositol mannoside and bound complement C3 less efficiently than H37Rv-HH; these differences were eliminated after treatment of H37Rv-CC with glass beads. Thus, outer capsular polysaccharides mediate the binding of H37Rv-CC to CR3, likely to the beta-glucan site. Moreover, there are strain-dependent differences in the thickness or composition of capsular polysaccharides that determine the mode of binding of M. tuberculosis to mammalian cells.
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PMID:Nonopsonic binding of Mycobacterium tuberculosis to complement receptor type 3 is mediated by capsular polysaccharides and is strain dependent. 931 35

Trypanosoma cruzi colonizes mainly the rectum of the vector, especially the rectal glands. We investigated the basic architecture of the rectal cuticle of Triatoma infestans and the mode of attachment of T. cruzi in the small intestine and the rectum. In addition, we determined the capacity of culture-derived epimastigotes to attach to artificial substrates and the influence of attachment on metacyclogenesis. After incubation of the rectum with wheat germ lectin (WGA) coupled to gold particles, the procuticle contained chitin, but the two layers of the epicuticle and the superficial layer bordering the rectal lumen did not. The specific fluorochrom Nile Red stained the entire rectal cuticle green, indicating the waxy composition of the superficial layer. In electron microscopic analysis the parasites were attached to the hydrophobic superficial wax layer but not to the epithelium of the midgut. In vitro culture-derived epimastigotes attached with a high affinity to all hydrophobic substrates tested, whereas hydrophilic substrates did not permit attachment. Emulsified hexadecane localized the attachment molecules to the terminal part of the flagellum. Inhibition of attachment by coating the culture tubes with hydrophilic agarose and constant agitation decreased the rate of epimastigote to trypomastigote transformation, whereas wax coating enhanced metacyclogenesis.
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PMID:Hydrophobic attachment of Trypanosoma cruzi to the rectal cuticle of Triatoma infestans and its influence on metacyclogenesis - a review. 1062 29

The hemagglutinating (HA) activity of Cratylia mollis lectin (Cra) was evaluated and the influence of ultrasound and mechanical agitation on its activity examined. The antitumor activity of Cra-loaded liposomes was also investigated. Liposomes were obtained by the lipid thin film method. Physicochemical characterization was carried out and long-term stability of Cra-loaded liposomes assessed. Antitumor activity of Cra-loaded liposomes was investigated against Sarcoma 180 in Swiss mice. The treatment was performed intraperitoneally (7 mg/kg body weight per day) for 7 days. Histopathological analyses of tumor, liver, spleen and kidneys were carried out after treatment of the animals. The results showed that Cra-HA activity is affected under ultrasound exposure. However, Cra was successfully encapsulated into liposomes and the activity of the lectin was preserved despite the use of ultrasound in the liposome preparation. Cra-loaded liposomes were produced with an 84% encapsulation ratio (700 microg/ml) and a tumor inhibition of 71% was achieved. The encapsulation of Cra produced a decrease in its tissue toxicity and improved its antitumor activity. In particular, histopathological analysis revealed that treatment with Cra-loaded liposomes prevented Cra cytotoxicity in the liver and kidney of animals.
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PMID:Antitumor activity of Cratylia mollis lectin encapsulated into liposomes. 1519 47

Specific aggregation and separation of microorganisms was investigated using yeasts and concanavalin A as a model system. Cells of Saccharomyces cerevisiae were specifically aggregated and so separated from those of Schizosaccharomyces pombe. Optimum aggregation with over 99% of cells aggregated was achieved by adjustment to pH value and applied agitation. Dimeric lectin structure caused a far higher degree of aggregation than did tetrameric. Degree of aggregation was also strongly influenced by the ratio of lectin/cell concentrations, optimum aggregation occurring in the middle range of ratios. A high ratio of lectin to cells inhibited aggregation, occupation of most of the available receptors preventing intercellular bonding by divalent lectins. Detachment and reuse of concanavalin A was demonstrated using switching from moderate to low pH value. Potential uses for species-specific-separation of microorganisms are discussed.
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PMID:Selective separation of microorganisms by lectins: yeast and concanavalin A as a model system. 1860 Nov 87