Escherichia coli virulence and renal scarring.
Explore the source record for details and available documents.
Escherichia coli↗
Biomedical subjects
N Topley
Publications and source records attributed to N Topley.
TPA-induced differentiation and adhesion of U937 cells: changes in ultrastructure, cytoskeletal organization and expression of cell surface antigens.
Incubation of the human promonocytic cell line U937 with 12-O-tetradecanoylphorbol-13-acetate (TPA) for 72 h resulted in differentiation into immature macrophage-like cells and was accompanied by marked morphological and functional changes. U937 cells which normally grow in suspension and show a smooth surface, extended pseudopodia and became adherent to each other and to the surface of the culture vessel. Concomitant with the TPA-induced adherence U937 cells ceased to proliferate. Our results show that phorbol ester-treated U937 cells exhibited markedly increased levels of fibronectin and of the cytoskeletal proteins actin, myosin and vimentin including a reorganization of actin and vimentin filaments. The induction of both cellular adherence and growth inhibition were accompanied by a significantly reduced level of cells expressing transferrin receptors and changes in cell surface antigen expression. Here, the expression of the leukocytefunction antigens (LFA-1), including CD11 and CD18 was markedly enhanced during phorbol ester-induced differentiation. TPA-treatment, however, failed to enhance the small amount of U937 cells expressing the monocyte/macrophage-specific CD14 antigen or expressing MHC class-II antigens. A detailed analysis of the CD14 cluster by 7 differential antibodies resulted in an induction of TM1, UCHM1, MEM15, My4, and 3C10, whereas the epitopes recognized by TM2 and Mo2 remained unaltered. Neither indomethacin nor interferon-gamma were capable of inducing a marked expression of these antigen epitopes in TPA-treated cells. Although these data demonstrate that during phorbol ester-induced differentiation U937 cells acquire many properties typically associated with macrophages, the failure to express marked levels of macrophage-specific cell surface antigens suggests a transition of U937 cells from a promonocytic to an immature macrophage intermediate state rather than into mature macrophage-like cells.
Antigens, Surface↗
Differences of the molecular structure of interleukin 1 binding proteins in functionally different cell types.
Explore the source record for details and available documents.
Animals↗
The effect of dialysate on peritoneal phagocyte oxidative metabolism.
The respiratory and oxidative responses of human peritoneal polymorphonuclear leukocytes (PMN) and peritoneal macrophages (PM phi) following exposure to unused continuous ambulatory peritoneal dialysis fluid (CAPD) and early dwell effluent were studied using an open oxygen (O2) electrode system and by measurement of oxygen radical-derived luminol-dependent chemiluminescence. Both cell types responded to stimulation by increasing O2 consumption and by generating chemiluminescence even at external O2 concentrations below 50 microM O2. Oxygen concentrations in the dialysate, as measured by blood gas analysis, were never lower than 118 +/- 8.3 microM O2 even during active peritonitis. Thus oxygen availability does not appear to be rate limiting for phagocyte oxidative metabolism in the peritoneal cavity. Preexposure of both inflammatory cell types to unused fluid or early dwell CAPD effluent significantly reduced both stimulated oxygen uptake and the subsequent ability of these cells to generate chemiluminescence without significantly affecting their viability. Further investigation of this down regulatory phenomenon using unused fluid and laboratory prepared dialysis fluid revealed that low pH (5.3) and high sodium lactate concentration in combination are directly responsible for the suppressive effect of unused fluid and early dwell effluent on cell function. These observations demonstrate that cellular host defense may be impaired early in the dialysis cycle as a result of lactate mediated "stunning" of resident phagocytes. The precise nature of the molecular species responsible for this suppressive effect remains to be identified.
Dialysis Solutions↗
Type 1 fimbriate Escherichia coli stimulates a unique pattern of degranulation by human polymorphonuclear leukocytes.
Uropathogenic strains of Escherichia coli bearing mannose-sensitive (type 1) fimbriae promote a unique pattern of degranulation from human polymorphonuclear leukocytes (PMN). Significant quantities of the primary (1 degree) and tertiary (3 degree) granule markers, neutral protease-myeloperoxidase and N-acetyl-beta-D-glucosaminidase, respectively, were released by PMN in a dose- and time-dependent manner when stimulated by these defined bacterial strains. Organisms bearing mannose-resistant (P) fimbriae promoted release of only the secondary (2 degree) granule marker, vitamin B12-binding protein. When this pattern of degranulation was compared to that produced by PMN in response to a variety of soluble and particulate stimuli, only the calcium ionophore A23187 similarly triggered 1 degree and 3 degree granule marker release. All the other stimuli tested--zymosan, serum-treated and unopsonized; n-formylmethionyl-leucyl-phenylalanine; and phorbol myristate acetate--promoted release of only the 2 degree granule marker. These results demonstrate selectivity of PMN degranulation in response to a number of transmembrane signals. In addition, the capacity of E. coli to promote PMN degranulation is dependent on its phenotypic fimbrial expression, a surface characteristic which correlates significantly with its relative surface hydrophobicity as measured by binding to octyl Sepharose. Those bacteria demonstrating the greatest hydrophobicity were capable of triggering discharge of all three granule marker proteins. Thus, the mannose-sensitive fimbriae of uropathogenic E. coli may contribute significantly to their potential pathophysiologic role in renal scarring.
Cytoplasmic Granules↗
Opsonic activity of dialysis effluent predicts those at risk of Staphylococcus epidermidis peritonitis.
The overnight effluent obtained from 62 patients undergoing CAPD was examined for IgG, C3 and C4 concentrations and for opsonic activity against S. epidermidis using polymorphonuclear leucocyte phagocytosis and luminol-dependent. chemiluminescence. There was a negative correlation between IgG and the age of the patient, but no relationship between IgG, C3 and C4, time on CAPD, or clinical diagnosis. Forty-eight of these patients were followed up for 6 months and 37 for a full year. An effluent IgG concentration of less than 0.105 g/l was associated with a significantly greater risk of infection with S. epidermidis during the study period. Comparing 'high' and 'low' values of C3 and C4, and using phagocytosis and chemiluminescence as measures of opsonic activity there were significant differences in the frequency of S. epidermidis peritonitis between the two groups during the follow up periods. No patient with high values of both IgG and C3 had S. epidermidis peritonitis during 12 months of study. Opsonic activity was both immunoglobulin and complement dependent. The latter activity involved both the classical and alternative complement pathways. These results suggest that routine screening of dialysate for IgG and C3 concentrations may be of prognostic value.
Adult↗
Factors affecting the measurement of chemiluminescence in stimulated human polymorphonuclear leucocytes.
Optimum conditions were established for the generation and measurement of luminol-dependent chemiluminescence (CL) in human polymorphonuclear leucocytes (PMNL) stimulated with a variety of particulate and soluble agents. Several factors had a particular influence on the kinetics of CL stimulated by the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). Two peaks, both azide-sensitive, were observed at 21 degrees C and 25 degrees C, but these increased in magnitude and merged to give a single, early peak when the temperature was increased at 37 degrees C. Pre-exposure of PMNL to a buffer containing calcium was essential for the expression of both phases of fMLP-stimulated CL, while the second peak decreased dramatically if the cells were stored at 4 degrees C for 4 hours before assay. In contrast, storage of PMNL at 4 degrees C for up to 8 hours in a buffer without divalent cations did not alter the kinetics or magnitude of CL induced by other stimuli, and had the benefit of minimizing the rate of cell aggregation. This study confirms that measurement of luminol-dependent CL in stimulated PMNL is a useful analytical tool, but shows that careful attention to experimental design is required to ensure that the observed CL provides a true measure of the parameter under investigation.
Humans↗
Virulence factors of urinary pathogens.
Explore the source record for details and available documents.
Cicatrix↗
Activation of human polymorphonuclear leucocytes by particulate zymosan is related to both its major carbohydrate components: glucan and mannan.
Unopsonized particulate zymosan and its major carbohydrate component glucan were phagocytosed under serum-free conditions by adherent polymorphonuclear leucocytes (PMN) in a dose- and time-dependent manner. Preincubation of PMN monolayers with mannan did not cause a reduction in the phagocytosis of either particle. The phagocytic response was inhibited by preincubation of the cells with trypsin at a concentration that did not inhibit the phagocytosis of sheep erythrocytes coated with IgG or of latex particles. Homology of the recognition mechanisms for glucan and zymosan was confirmed when cells cultured on fixed glucan or on fixed zymosan failed to ingest either particle to more than 40% of control phagocytosis. Similarly, zymosan and glucan activated PMN in suspension, in a dose- and time-dependent manner, to generate reactive oxygen species which were measured as luminol-dependent chemiluminescence (CL). There was, however, a four-fold greater CL response to zymosan. Preincubation of PMN with mannan resulted in a significantly decreased CL response to zymosan, while the response to glucan was unaffected. The CL response was also sensitive to a range of concentrations of trypsin. In contrast, two other complex polysaccharide particles (barley-derived beta-glucan and algae-derived laminarin) were not phagocytosed by PMN, nor did they cause the generation of CL, despite the fact that they possessed the capacity, in common with zymosan and glucan, to activate the alternative pathway of complement. The identification of a trypsin-sensitive recognition mechanism on the surface of human PMN for unopsonized zymosan and glucan represents a response not hitherto characterized. Furthermore, our data indicate that the phagocytosis of unopsonized zymosan by human PMN is dependent primarily on its glucan content, but that its capacity to activate the respiratory burst may involve mannan and the recruitment of a second cell surface recognition mechanism.
Complement Activation↗
Differential biological activities of human interleukin-1 alpha and interleukin-1 beta.
We examined the biological effects induced by both human recombinant interleukin-1 alpha (IL-1 alpha) and beta (IL-1 beta) in five different cell types of human, rat and mouse origin. IL-1 alpha and beta preparations were standardized in terms of biological activity in the EL-4/CTLL bioassay and, in parallel, employed to stimulate PGE2 secretion in human fibroblasts, mesangial cells (MC), C57B1/6 mouse MC, DBA/2 mouse macrophages and Sprague Dawley rat MC. In addition, the co-mitogenic effects of IL-1 alpha and beta were determined in freshly prepared Sprague Dawley rat thymocytes. No significant differences in IL-1 alpha and beta concentration dependent PGE2 production were detectable in the different cell types (MC, fibroblasts and macrophages) of human or mouse origin. Incubation of Sprague Dawley rat MC with both IL-1 alpha and beta resulted in a concentration dependent production of PGE2. However, in contrast to mouse or human MC the potency of IL-1 beta to induce PGE2 in Sprague Dawley rat MC was 26-fold higher compared to IL-1 alpha. In addition, the potency of IL-1 beta to enhance co-stimulated proliferation of Sprague Dawley thymocytes was 200-fold higher than that of equal biological activities of IL-1 alpha. When we tested the additive effects on Sprague Dawley cells, increasing IL-1 beta concentrations added to a fixed IL-1 alpha concentration resulted in a cumulative rise in both, PGE2 secretion by MC and thymocyte proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
What is the ideal technique for testing the biocompatibility of peritoneal dialysis solutions?
Explore the source record for details and available documents.
Biocompatible Materials↗
PDGF-BB, but not PDGF-AA, stimulates calcium mobilization, activation of calcium channels and cell proliferation in cultured rat mesangial cells.
The effects of different isoforms of platelet-derived growth factor (PDGF) on cellular growth and on cytoplasmic Ca2+ levels in mesangial cells using a microfluorometric system and the calcium indicator FURA-2 were investigated. A rapid increase of cytoplasmic calcium in response to PDGF-BB was found and in the presence of 1.25 mM extracellular calcium, the resting level of cytoplasmic calcium following the initial peak was significantly increased compared with a calcium-free medium, but was completely attenuated with the calcium channel blocker verapamil (50 microM). PDGF-AA did not cause any increase in cytoplasmic calcium. In growth arrested MC PDGF-BB, but not PDGF-AA, also enhanced cell growth. It is concluded that cultured rat mesangial cells react to PDGF-BB but not to PDGF-AA with a rapid mobilization of intracellular calcium followed by subsequent activation of calcium channels and a stimulation of cell growth. A PDGF-BB driven mechanism for MC proliferation in inflammatory and metabolic glomerular diseases is suggested.
Animals↗
In vitro biocompatibility of bicarbonate-based peritoneal dialysis solutions.
OBJECTIVE: To review the current literature on the in vitro biocompatibility of peritoneal dialysis solutions buffered with bicarbonate and compare them to existing conventional lactate-buffered solutions. RESULTS: Conventional lactate-buffered solutions are known to inhibit or modulate cell functions related to host defense mechanisms; these effects are mediated by their low pH in combination with lactate concentration, as well as their glucose content, associated osmolality, and the presence of glucose breakdown products. CONCLUSIONS: Bicarbonate-buffered solutions appear to present a viable alternative for use in CAPD based on their significantly improved biocompatibility profile. The results of on-going clinical trials will clarify whether these in vitro data will impact significantly on peritoneal host defence, infection rate and the long term function of the peritoneal membrane in vivo.
Bicarbonates↗
Insulin stimulates the activity of Na+/K(+)-ATPase in human peritoneal mesothelial cells.
OBJECTIVE: To assess the effect of insulin on the Na+/K(+)-ATPase expression and activity in human peritoneal mesothelial cells (HPMC). METHODS: HPMC were isolated from the omental tissue of non-uremic patients, grown to confluence and rendered quiescent by serum deprivation for 24 hours. The activity of Na+/K(+)-ATPase was determined by measuring the ouabain-sensitive 86Rb uptake. To assess whether the effect of insulin was related to changes in [Na+]i the sodium influx was measured with 22Na and the activity of Na+/K(+)-ATPase was assessed in the presence of amiloride. Expression of Na+/K(+)-ATPase alpha 1,alpha 2 and beta 1-subunit mRNAs was determined by RT/PCR. RESULTS: Exposure of HPMC to insulin resulted in a time- and dose-dependent increase in the Na+/K(+)-ATPase activity. After 60 minutes the ouabain-sensitive 86Rb uptake (cpm/10(4) cells) was increased from 6650 +/- 796 in control cells to 9763 +/- 1212 in HPMC exposed to 100 mU/mL insulin (1.5-fold increase; n = 4, P < 0.05). In addition, incubation of HPMC with 100 mU/mL insulin resulted in a time-dependent increase in the 22Na influx. Pre-exposure of HPMC to 1mM amiloride reduced the activity of Na+/K(+)-ATPase but did not block the stimulatory effect of insulin. RT/PCR analysis revealed that HPMC constitutively expressed alpha 1- and beta 1-subunit mRNAs while the alpha 2-subunit mRNA was barely detectable. Exposure of HPMC to insulin for up to 24 hours was not associated with any changes in the expression of either alpha 1, alpha 2 or beta 1-subunit. CONCLUSION: Insulin stimulates the Na+/K(+)-ATPase activity in HPMC in a time- and dose-dependent manner. This effect appears to mediated by an increase in [Na+]i and is not related to alterations in Na+/K(+)-ATPase subunit mRNAs expression.
Cells, Cultured↗