scholarly journals Bibersteinia trehalosi Inhibits the Growth of Mannheimia haemolytica by a Proximity-Dependent Mechanism

2009 ◽  
Vol 76 (4) ◽  
pp. 1008-1013 ◽  
Author(s):  
Rohana P. Dassanayake ◽  
Douglas R. Call ◽  
Ashish A. Sawant ◽  
N. Carol Casavant ◽  
Glen C. Weiser ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Pore Size ◽  
Cell Density ◽  
Pasteurella Multocida ◽  
Growth Curves ◽  
Ovis Canadensis ◽  
Experimental Conditions ◽  
Bacterial Populations ◽  
Bibersteinia Trehalosi ◽  
Dependent Mechanism

ABSTRACT Mannheimia (Pasteurella) haemolytica is the only pathogen that consistently causes severe bronchopneumonia and rapid death of bighorn sheep (BHS; Ovis canadensis) under experimental conditions. Paradoxically, Bibersteinia (Pasteurella) trehalosi and Pasteurella multocida have been isolated from BHS pneumonic lungs much more frequently than M. haemolytica. These observations suggest that there may be an interaction between these bacteria, and we hypothesized that B. trehalosi overgrows or otherwise inhibits the growth of M. haemolytica. Growth curves (monoculture) demonstrated that B. trehalosi has a shorter doubling time (∼10 min versus ∼27 min) and consistently achieves 3-log higher cell density (CFU/ml) compared to M. haemolytica. During coculture M. haemolytica growth was inhibited when B. trehalosi entered stationary phase (6 h) resulting in a final cell density for M. haemolytica that was 6 to 9 logs lower than expected with growth in the absence of B. trehalosi. Coculture supernatant failed to inhibit M. haemolytica growth on agar or in broth, indicating no obvious involvement of lytic phages, bacteriocins, or quorum-sensing systems. This observation was confirmed by limited growth inhibition of M. haemolytica when both pathogens were cultured in the same media but separated by a filter (0.4-μm pore size) that limited contact between the two bacterial populations. There was significant growth inhibition of M. haemolytica when the populations were separated by membranes with a pore size of 8 μm that allowed free contact. These observations demonstrate that B. trehalosi can both outgrow and inhibit M. haemolytica growth with the latter related to a proximity- or contact-dependent mechanism.

scholarly journals Proximity-Dependent Inhibition of Growth of Mannheimia haemolytica by Pasteurella multocida

2012 ◽  
Vol 78 (18) ◽  
pp. 6683-6688 ◽  
Author(s):  
Jegarubee Bavananthasivam ◽  
Rohana P. Dassanayake ◽  
Abirami Kugadas ◽  
Sudarvili Shanthalingam ◽  
Douglas R. Call ◽  
...  
Keyword(s):  
Pore Size ◽  
Pasteurella Multocida ◽  
Ovis Canadensis ◽  
Mannheimia Haemolytica ◽  
Experimental Conditions ◽  
Content Type ◽  
Inhibition Of Growth ◽  
Dependent Inhibition ◽  
Bibersteinia Trehalosi

ABSTRACTMannheimia haemolytica,Pasteurella multocida, andBibersteinia trehalosihave been identified in the lungs of pneumonic bighorn sheep (BHS;Ovis canadensis). Of these pathogens,M. haemolyticahas been shown to consistently cause fatal pneumonia in BHS under experimental conditions. However,M. haemolyticahas been isolated by culture less frequently than the other bacteria. We hypothesized that the growth ofM. haemolyticais inhibited by other bacteria in the lungs of BHS. The objective of this study was to determine whetherP. multocidainhibits the growth ofM. haemolytica. Although in monoculture both bacteria exhibited similar growth characteristics, in coculture withP. multocidathere was a clear inhibition of growth ofM. haemolytica. The inhibition was detected at mid-log phase and continued through the stationary phase. When cultured in the same medium, the growth ofM. haemolyticawas inhibited when both bacteria were separated by a membrane that allowed contact (pore size, 8.0 μm) but not when they were separated by a membrane that limited contact (pore size, 0.4 μm). Lytic bacteriophages or bactericidal compounds could not be detected in the culture supernatant fluid from monocultures ofP. multocidaor fromP. multocida-M. haemolyticacocultures. These results indicate thatP. multocidainhibits the growth ofM. haemolyticaby a contact- or proximity-dependent mechanism. If the inhibition of growth ofM. haemolyticabyP. multocidaoccursin vivoas well, it could explain the inconsistent isolation ofM. haemolyticafrom the lungs of pneumonic BHS.

scholarly journals Single-Sided Portable NMR Investigation to Assess and Monitor Cleaning Action of PVA-Borax Hydrogel in Travertine and Lecce Stone

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3697
Author(s):  
Valeria Stagno ◽  
Chiara Genova ◽  
Nicole Zoratto ◽  
Gabriele Favero ◽  
Silvia Capuani
Keyword(s):  
Pore Size ◽  
Experimental Conditions ◽  
Non Invasive ◽  
Bedding Planes ◽  
Paramagnetic Impurities ◽  
Two Samples ◽  
Action Time ◽  
Paramagnetic Agents ◽  
Portable Nmr ◽  
Non Destructive

In this work, we investigated the potential of PVA-borax hydrogel for cleaning limestones and the dependence of the cleaning on the porosity of the rock and on the action time of the hydrogel treatment. Towards this goal, we used a nuclear magnetic resonance (NMR) spectrometer, developed for non-invasive and non-destructive applications on cultural heritage. T2-NMR parameters were quantified on different samples of Lecce stone and Travertine cut perpendicular (Pe) and parallel (Pa) to the bedding planes under different experimental conditions: untreated samples, treated with Paraloid B72 and cleaned with PVA-PEO-borax hydrogel applied for 4 min and 2 h. The T2 results suggest that the effectiveness of the cleaning strongly depended on the porosity of the stones. In Lecce stone, the hydrogel seemed to eliminate both the paramagnetic impurities (in equal measure with 4 min and 2 h treatment) and Paraloid B72. In Travertine Pe, characterized by a smaller pore size compared to Lecce stone, no significant effects were found regarding both the cleaning and the treatment with Paraloid B72. In Travertine Pa, characterized by a larger pore size than the other two samples, the hydrogel seemed to clean the paramagnetic agents (it worked better if applied for a longer time) but it did not appear to have any effect on Paraloid B72 removal.

scholarly journals Stochasticity in Colonial Growth Dynamics of Individual Bacterial Cells

2013 ◽  
Vol 79 (7) ◽  
pp. 2294-2301 ◽  
Author(s):  
Konstantinos P. Koutsoumanis ◽  
Alexandra Lianou
Keyword(s):  
Kinetic Parameters ◽  
Single Cells ◽  
Growth Curves ◽  
Growth Dynamics ◽  
Time Lapse ◽  
Initial Population ◽  
Bacterial Cells ◽  
Stochastic Growth ◽  
Bacterial Populations ◽  
Content Type

ABSTRACTConventional bacterial growth studies rely on large bacterial populations without considering the individual cells. Individual cells, however, can exhibit marked behavioral heterogeneity. Here, we present experimental observations on the colonial growth of 220 individual cells ofSalmonella entericaserotype Typhimurium using time-lapse microscopy videos. We found a highly heterogeneous behavior. Some cells did not grow, showing filamentation or lysis before division. Cells that were able to grow and form microcolonies showed highly diverse growth dynamics. The quality of the videos allowed for counting the cells over time and estimating the kinetic parameters lag time (λ) and maximum specific growth rate (μmax) for each microcolony originating from a single cell. To interpret the observations, the variability of the kinetic parameters was characterized using appropriate probability distributions and introduced to a stochastic model that allows for taking into account heterogeneity using Monte Carlo simulation. The model provides stochastic growth curves demonstrating that growth of single cells or small microbial populations is a pool of events each one of which has its own probability to occur. Simulations of the model illustrated how the apparent variability in population growth gradually decreases with increasing initial population size (N0). For bacterial populations withN0of >100 cells, the variability is almost eliminated and the system seems to behave deterministically, even though the underlying law is stochastic. We also used the model to demonstrate the effect of the presence and extent of a nongrowing population fraction on the stochastic growth of bacterial populations.

Amino acid uptake regulation by cell growth in cultured hepatocytes isolated from fetal and adult rats

1992 ◽  
Vol 12 (2) ◽  
pp. 135-141 ◽  
Author(s):  
S. Leoni ◽  
S. Spagnuolo ◽  
M. Massimi ◽  
F. Terenzi ◽  
L. Conti Devirgiliis
Keyword(s):  
Amino Acid ◽  
Cell Growth ◽  
Growth Inhibition ◽  
Cell Density ◽  
Amino Acid Uptake ◽  
Growth Stimulation ◽  
Acid Uptake ◽  
Adult Rats ◽  
Dependent Growth ◽  
Differentiation Stage

Amino acid uptake mediated by system A was studied in cultured fetal and adult hepatocytes, subjected to growth stimulation by EGF and insulin, or to growth inhibition by high cell density. The mitogenic stimulation induced a strong transport increase only in fetal cells, while the cell density-dependent growth inhibition, probably mediated by molecules present on adult hepatocyte membranes, provoked the decrease of amino acid uptake only in the adult cells. The results indicate that the different modulation of amino acid transport by cell growth is dependent on the age and the differentiation stage of hepatocytes.

scholarly journals Comparison of Passively Transferred Antibodies in Bighorn and Domestic Lambs Reveals One Factor in Differential Susceptibility of These Species to Mannheimia haemolytica-Induced Pneumonia

2011 ◽  
Vol 18 (7) ◽  
pp. 1133-1138 ◽  
Author(s):  
Caroline N. Herndon ◽  
Sudarvili Shanthalingam ◽  
Donald P. Knowles ◽  
Douglas R. Call ◽  
Subramaniam Srikumaran
Keyword(s):  
Differential Susceptibility ◽  
Critical Factor ◽  
Surface Antigens ◽  
Ovis Canadensis ◽  
Ovis Aries ◽  
Mannheimia Haemolytica ◽  
Domestic Sheep ◽  
Experimental Conditions ◽  
Content Type ◽  
Impaired Ability

ABSTRACTMannheimia haemolyticaconsistently causes fatal bronchopneumonia in bighorn sheep (BHS;Ovis canadensis) under natural and experimental conditions. Leukotoxin is the primary virulence factor of this organism. BHS are more susceptible to developing fatal pneumonia than the related speciesOvis aries(domestic sheep [DS]). In BHS herds affected by pneumonia, lamb recruitment is severely impaired for years subsequent to an outbreak. We hypothesized that a lack of maternally derived antibodies (Abs) againstM. haemolyticaprovides an immunologic basis for enhanced susceptibility of BH lambs to population-limiting pneumonia. Therefore, the objective of this study was to determine the titers of Abs directed againstM. haemolyticain the sera of BH and domestic lambs at birth through 12 weeks of age. Results revealed that BH lambs had approximately 18-fold lower titers of Ab against surface antigens ofM. haemolyticaand approximately 20-fold lower titers of leukotoxin-neutralizing Abs than domestic lambs. The titers of leukotoxin-neutralizing Abs in the serum and colostrum samples of BH ewes were approximately 157- and 50-fold lower than those for domestic ewes, respectively. Comparatively, the higher titers of parainfluenza 3 virus-neutralizing Abs in the BH lambs ruled out the possibility that these BHS had an impaired ability to passively transfer Abs to their lambs. These results suggest that lower levels of leukotoxin-neutralizing Abs in the sera of BH ewes, and resultant low Ab titers in their lambs, may be a critical factor in the poor lamb recruitment in herds affected by pneumonia.

Different mechanisms in the attachment of cells to native and denatured collagen

1979 ◽  
Vol 38 (1) ◽  
pp. 267-281
Author(s):  
S.L. Schor ◽  
J. Court
Keyword(s):  
Cell Attachment ◽  
Experimental Conditions ◽  
Cell Matrix ◽  
Matrix Interactions ◽  
Independent Mechanism ◽  
Cell Matrix Interactions ◽  
Serum Dependent ◽  
Kinetics Of ◽  
Dependent Mechanism

The attachment of cells to collagen has been reported previously to require the presence of serum and the particular serum protein involved in this process, variously known as CIG, CAP or fibronectin, has been isolated. This conclusion that cell attachment to collagen requires serum (or more precisely, fibronectin) is based on experiments measuring the kinetics of cell attachment to films of collagen. We have measured the kinetics of attachment of HeLa and attachment to films of collagen-containing substrata under a variety of experimental conditions and present evidence that the serum-dependent mechanism of cell attachment described by others is actually only the case for films of denatured collagen, while cell attachment to native collagen fibres occurs by a different, serum-independent, mechanism. The possible relevance of these findings to cell-matrix interactions in vivo is discussed.

Abstract 27: ApoA-I Improves Lymphatic Function Through a Platelet-Dependent Mechanism in Atherosclerotic Mice

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Andreea Milasan ◽  
François Dallaire ◽  
Gabriel Jean ◽  
Jean-Claude Tardif ◽  
Yahye Merhi ◽  
...  
Keyword(s):  
Lymphatic Vessel ◽  
Ex Vivo ◽  
Lymphatic Vessels ◽  
Lymphatic Transport ◽  
Lv Function ◽  
Experimental Conditions ◽  
Lymphatic Function ◽  
Beneficial Effects ◽  
Dependent Mechanism

Rationale: Lymphatic vessels (LVs) are now recognized as prerequisite players in the modulation of cholesterol removal from the artery wall in experimental conditions of plaque regression, and a particular attention has been brought on the role of the collecting LVs in early atherosclerosis-related lymphatic dysfunction. Whereas recent findings revealed that apoA-I restores the neovascularization capacity of the lymphatic system during tumor necrosis factor-induced inflammation, the effect of apoA-I on collecting LV function during atherosclerosis has not been tested. Objective: In the present study, we address whether and how apoA-I can enhance collecting LV function in atherosclerosis-associated lymphatic dysfunction. Methods and Results: A 6-week systemic treatment with lipid-free apoA-I enhanced lymphatic transport and abrogated collecting lymphatic vessel permeability in atherosclerotic Ldlr –/– mice when compared to control. As injection of apoA-I has been shown to protect wild-type mice against flow restriction-induced thrombosis, and that platelets are identified as key elements in the maintenance of lymphatic vessel integrity via their interaction with lymphatic endothelial cells (LECs), we have tested whether the effects of apoA-I could be mediated through a platelet-dependent mechanism. Our in vivo results show that apoA-I kinetics in lymph reflected that of blood. Ex vivo experiments performed with washed platelets isolated from mouse blood reveal that apoA-I decreased thrombin-induced but not podoplanin-induced platelet aggregation. Whereas this result suggests that apoA-I limits platelet thrombotic potential in blood but not in lymph, we demonstrate that treatment of human LECs with apoA-I increases the adhesion of bridge-like platelets on human LECs. Conclusions: Our results suggest that apoA-I can mediate beneficial effects on lymphatic function by promoting platelet adhesion to the lymphatic endothelium and consequently restore collecting LV integrity. Altogether, we bring forward a new pleiotropic role for apoA-I in lymphatic function and unveil new potential therapeutic targets for the prevention and treatment of atherosclerosis.

A Comparison of CO2 and N2 Foaming Behaviors of PP in a Visualization System

2020 ◽  
Vol 35 (5) ◽  
pp. 503-517
Author(s):  
Q.-P. Guo ◽  
J. Wang ◽  
C. B. Park
Keyword(s):  
Cell Density ◽  
Nucleating Agent ◽  
Gas Content ◽  
Experimental Conditions ◽  
Maximum Cell Density ◽  
Visualization System ◽  
Cell Nucleation ◽  
Processing Strategies ◽  
Automotive Parts ◽  
Maximum Cell

Abstract Understanding of polypropylene (PP) foaming is critically important to reduce the weight of automotive parts. In this study, we used a batch foaming simulation system with visualization cell, to observe the foaming behaviors of PP that is blown with CO2 and N2 under various experimental conditions. We found that the nucleating agent content, initial temperature, pressure (i. e., gas content), and pressure drop rate during foaming have a significant effect on cell nucleation and cell growth. The cell density and the void fraction of PP foamed with CO2 and N2, respectively, were separately observed and compared. It was found that under the same experimental conditions, the maximum cell density of PP foamed with CO2 was higher than that of PP foamed with N2. However, the maximum cell density of PP foamed with CO2 was determined to be lower than that of PP foamed with N2, when the same gas mole numbers were employed. Based on the experimental results, optimum foaming conditions and effective processing strategies for PP-CO2 system are suggested.

scholarly journals Effects of Encapsulated Cells on the Physical–Mechanical Properties and Microstructure of Gelatin Methacrylate Hydrogels

2019 ◽  
Vol 20 (20) ◽  
pp. 5061 ◽  
Author(s):  
Srikumar Krishnamoorthy ◽  
Behnam Noorani ◽  
Changxue Xu
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Cell Viability ◽  
Physical Properties ◽  
Pore Size ◽  
Cell Density ◽  
Tensile Modulus ◽  
Encapsulated Cells ◽  
3T3 Fibroblasts ◽  
Cell Densities

Gelatin methacrylate (GelMA) has been gaining popularity in recent years as a photo-crosslinkable biomaterial widely used in a variety of bioprinting and tissue engineering applications. Several studies have established the effects of process-based and material-based parameters on the physical–mechanical properties and microstructure of GelMA hydrogels. However, the effect of encapsulated cells on the physical–mechanical properties and microstructure of GelMA hydrogels has not been fully understood. In this study, 3T3 fibroblasts were encapsulated at different cell densities within the GelMA hydrogels and incubated over 96 h. The effects of encapsulated cells were investigated in terms of mechanical properties (tensile modulus and strength), physical properties (swelling and degradation), and microstructure (pore size). Cell viability was also evaluated to confirm that most cells were alive during the incubation. It was found that with an increase in cell density, the mechanical properties decreased, while the degradation and the pore size increased.

scholarly journals In Vivo Targets of Pasteurella Multocida Toxin

2020 ◽  
Vol 21 (8) ◽  
pp. 2739
Author(s):  
Arshiya Banu ◽  
Alistair J. Lax ◽  
Agamemnon E. Grigoriadis
Keyword(s):  
G Proteins ◽  
Protein Modification ◽  
Pasteurella Multocida ◽  
Term Treatment ◽  
Atrophic Rhinitis ◽  
Short Term Treatment ◽  
Experimental Conditions ◽  
Proliferation Markers ◽  
Pasteurella Multocida Toxin

Many Pasteurella multocida strains are carried as commensals, while some cause disease in animals and humans. Some type D strains cause atrophic rhinitis in pigs, where the causative agent is known to be the Pasteurella multocida toxin (PMT). PMT activates three families of G-proteins—Gq/11, G12/13, and Gi/o—leading to cellular mitogenesis and other sequelae. The effects of PMT on whole animals in vivo have been investigated previously, but only at the level of organ-specific pathogenesis. We report here the first study to screen all the organs targeted by the toxin by using the QE antibody that recognizes only PMT-modified G-proteins. Under our experimental conditions, short-term treatment of PMT is shown to have multiple in vivo targets, demonstrating G-alpha protein modification, stimulation of proliferation markers and expression of active β-catenin in a tissue- and cell-specific manner. This highlights the usefulness of PMT as an important tool for dissecting the specific roles of different G-alpha proteins in vivo.

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