scholarly journals Isolate differences in colonization efficiency during experimental human pneumococcal challenge

2020 ◽  
Author(s):  
Sherin Pojar ◽  
Alan Basset ◽  
Jenna F. Gritzfeld ◽  
Elissavet Nikolaou ◽  
Saskia van Selm ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Epithelial Cell ◽  
Chain Length ◽  
Healthy Adults ◽  
Average Chain Length ◽  
Cell Adherence ◽  
Microbial Characteristics ◽  
Kinetics Of ◽  
Experimental Challenge ◽  
Colonization Rates

SummaryColonization efficiency varies considerably between Streptococcus pneumoniae (pneumococcus) strains. The microbial characteristics that influence those differences are still largely unknown. Here, we report rates and kinetics of colonization of four pneumococcal strains upon experimental human pneumococcal challenge. Healthy adults were intranasally challenged with one of four pneumococcal strains (serotype/clonal name: 6B/BHN418, 15B/SH8286, 23F/P1121 and 23F/P833) over a range of doses. Maximum colonization achieved was 60%, 31%, 16% and 10%, respectively. Density and duration of colonization did not differ significantly between the tested strains. We further evaluated murine colonization, non-opsonic neutrophil mediated killing, epithelial cell adherence and average chain length of these four pneumococcal strains. Of these, only chain length was found to be associated with colonization efficiency in the human challenge model. Our data demonstrate that colonization rates following experimental challenge vary with the strain used and suggest that efficiency in colonization is related to pneumococcal chain length.

The thermal oxidation of methylene chloride

1959 ◽  
Vol 250 (1261) ◽  
pp. 197-211 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Chain Length ◽  
Methylene Chloride ◽  
Decomposition Reaction ◽  
Average Chain Length ◽  
Static System ◽  
Chain Process ◽  
Branched Chain ◽  
Considerable Detail ◽  
Kinetics Of

A study of the kinetics of the slow oxidation of methylene chloride has been made using a static system and the results of this are compared with those of flow-system experiments in which the composition of the reacting system was determined in considerable detail by gaschromatographic analysis. The reaction shows all the symptoms of a degenerately branched chain process and is similar to the corresponding thermal decomposition reaction in many respects. Several of the chlorinated hydrocarbon minor products are identical with those found in the thermal decomposition and this, together with kinetic evidence, suggests that the primary chain is the same in both reactions, oxygen intervening only in the conversion of the intermediate, dichlorethylene, to the end products HCl and carbon monoxide, and in the branching step, through which it modifies the overall rate. As in the thermal decomposition several of the organic minor products are susceptible to attack by chlorine atoms participating in the main chain and this prevents an accurate evaluation of the chain length by measurement of the rate of formation of termination products. The average chain length, however, appears to be of the order of ten. Methylene chloride + oxygen mixtures show a single explosion limit above about 600° C, which obeys the Semenov equation log 10 p = A / T + B , A being a constant for the system and B depending on the geometry of the vessel.

scholarly journals The nose is the best niche for detection of pneumococcal colonisation following experimental challenge in adults of all ages

2021 ◽  
Author(s):  
Elissavet Nikolaou ◽  
Esther Lauryn German ◽  
Annie Blizard ◽  
Ashleigh Howard ◽  
Lisa Hitchins ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Streptococcus Pneumoniae ◽  
Healthy Adults ◽  
Nasal Wash ◽  
Multiplex Qpcr ◽  
Post Exposure ◽  
Oropharyngeal Swab ◽  
Experimental Challenge

Abstract Background Previous studies have suggested that the pneumococcal niche changes from the nose to the oropharynx with age. We use an Experimental Human Pneumococcal Challenge model to investigate pneumococcal colonisation in each anatomical niche with age. Methods Healthy adults (n = 112) were intranasally inoculated with Streptococcus pneumoniae serotype 6B (Spn6B) and were categorised as young 18-55yrs (n = 57) or older > 55yrs (n = 55). Colonisation status (frequency and density) was determined by multiplex qPCR targeting the lytA and cpsA-6A/B genes in both raw and culture-enriched nasal wash and oropharyngeal swab samples collected at 2-, 7- and 14-days post-exposure. For older adults, raw and culture-enriched saliva samples were also assessed. Results 64% of NW samples and 54% of OPS samples were positive for Spn6B in young adults, compared to 35% of NW samples, 24% of OPS samples and 6% of saliva samples in older adults. Many colonisation events were only detected in culture-enriched samples. Experimental colonisation was detected in 72% of young adults by NW and 63% by OPS. In older adults, this was 51% by NW, 36% by OPS and 9% by saliva. Conclusions The nose is the best niche for detection of experimental pneumococcal colonisation in both young and older adults.

Röntgenbeugungsuntersuchung an geschmolzenem Selen und Tellur sowie an Legierungen des Systems Selen—Tellur/ X-ray Diffraction Study of Molten Selenium, and Tellurium and of Molten Selenium — Tellurium-Alloys

1975 ◽  
Vol 30 (12) ◽  
pp. 1633-1639 ◽  
Author(s):  
W. Hoyer ◽  
E. Thomas ◽  
M. Wobst
Keyword(s):  
Chain Length ◽  
Short Range ◽  
Short Range Order ◽  
Coordination Shell ◽  
Range Order ◽  
Average Chain Length ◽  
X Ray Diffraction ◽  
Coordination Numbers ◽  
Nearest Neighbours ◽  
Increasing Temperature

Abstract At temperatures just above the melting point molten Selenium seems to be a mixture of long chains and eight-membered rings. With increasing temperature the number of rings and the average chain length decrease. At 460 °C the average chain length lies in the range of 10 atoms.In a slightly supercooled Tellurium-melt the number of first neighbours is two. The atoms are arranged in chains. Selenium rich Se-Te-alloy-melts are built up of mixed chains. It seems to be possible, that a smaller part of atoms forms Se6Te2 rings. At Tellurium concentrations higher than approximately 50 at.-% the chainlike structure with two next nearest neighbours changes to a disturbed Arsen-like short range order. The number of electrons in the first coordination shell, the short range order parameter introduced by Cowley and the partial coordination numbers show that Se-Te-alloys are of the "solution system" type, but in the whole concentration range for each atom there is a tendency to have "strange coordination".

scholarly journals Prenylation of Saccharomyces cerevisiae Chs4p Affects Chitin Synthase III Activity and Chitin Chain Length

2006 ◽  
Vol 6 (2) ◽  
pp. 328-336 ◽  
Author(s):  
Kariona A. Grabińska ◽  
Paula Magnelli ◽  
Phillips W. Robbins
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chain Length ◽  
Attachment Site ◽  
Chitin Synthase ◽  
Yeast Cells ◽  
Average Chain Length ◽  
Calcofluor White ◽  
Protein Factor

ABSTRACT Chs4p (Cal2/Csd4/Skt5) was identified as a protein factor physically interacting with Chs3p, the catalytic subunit of chitin synthase III (CSIII), and is indispensable for its enzymatic activity in vivo. Chs4p contains a putative farnesyl attachment site at the C-terminal end (CVIM motif) conserved in Chs4p of Saccharomyces cerevisiae and other fungi. Several previous reports questioned the role of Chs4p prenylation in chitin biosynthesis. In this study we reinvestigated the function of Chs4p prenylation. We provide evidence that Chs4p is farnesylated by showing that purified Chs4p is recognized by anti-farnesyl antibody and is a substrate for farnesyl transferase (FTase) in vitro and that inactivation of FTase increases the amount of unmodified Chs4p in yeast cells. We demonstrate that abolition of Chs4p prenylation causes a ∼60% decrease in CSIII activity, which is correlated with a ∼30% decrease in chitin content and with increased resistance to the chitin binding compound calcofluor white. Furthermore, we show that lack of Chs4p prenylation decreases the average chain length of the chitin polymer. Prenylation of Chs4p, however, is not a factor that mediates plasma membrane association of the protein. Our results provide evidence that the prenyl moiety attached to Chs4p is a factor modulating the activity of CSIII both in vivo and in vitro.

scholarly journals toxB Gene on pO157 of Enterohemorrhagic EscherichiacoliO157:H7 Is Required for Full Epithelial Cell Adherence Phenotype

2001 ◽  
Vol 69 (11) ◽  
pp. 6660-6669 ◽  
Author(s):  
Ichiro Tatsuno ◽  
Masanori Horie ◽  
Hiroyuki Abe ◽  
Takeyoshi Miki ◽  
Kozo Makino ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Bacterial Infection ◽  
Intestinal Epithelium ◽  
Secreted Proteins ◽  
Cell Adherence ◽  
Full Adherence ◽  
Infection Study ◽  
Phenotype Expression

ABSTRACT Adherence of enterohemorrhagic Escherichia coli (EHEC) to the intestinal epithelium is critical for initiation of a bacterial infection. An in vitro infection study previously indicated that EHEC bacteria initially adhere diffusely and then proliferate to develop MC, a process that is mediated by various secreted proteins, such as EspA, EspB, EspD, Tir, and intimin, as well as other putative adherence factors. In the present study, we investigated the role of a large 93-kb plasmid (pO157) in the adherence of O157:H7 (O157Sakai) and found the toxB gene to be involved in the full adherence phenotype. A pO157-cured strain of O157Sakai (O157Cu) developed microcolonies on Caco-2 cells; however, the number of microcolonies was lower than that of O157Sakai, as were the production and secretion levels of EspA, EspB, and Tir. Introduction of a mini-pO157 plasmid (pIC37) composed of thetoxB and ori regions restored full adherence capacity to O157Cu, including production and secretion of the proteins. In contrast, introduction of a pO157 mutant possessingtoxB::Km into O157Cu could not restore the full adherence phenotype. Expression of truncated versions of His-tagged ToxB also promoted EspB production and/or secretion by O157Cu. These results suggest that ToxB contributes to the adherence of EHEC to epithelial cells through promotion of the production and/or secretion of type III secreted proteins.

The Kinetics of Free-Radical Polymerization: Fundamental Aspects

2002 ◽  
Vol 55 (7) ◽  
pp. 399 ◽  
Author(s):  
G. T. Russell
Keyword(s):  
Molecular Weight ◽  
Steady State ◽  
Free Radical ◽  
Radical Polymerization ◽  
Chain Length ◽  
Free Radical Polymerization ◽  
Length Dependence ◽  
Model Independent ◽  
Living Free Radical Polymerization ◽  
Kinetics Of

Some fundamental aspects of the kinetics of free-radical polymerization are reviewed. So-called classical results for rate and molecular-weight distribution are first of all presented. It is shown how this approach can be built upon when chain-length-dependent termination is allowed, which it always should be. Various termination models are considered, and it is illustrated that although the models are different, rather remarkably they give common, model-independent behaviour. Some leading experimental results regarding the chain-length dependence of termination are summarized, before the chain-length dependence of other reactivities, the variation of reactivities with conversion, and non-steady state experiments are briefly discussed. Finally, living free-radical polymerization as effected by a reversible termination agent is considered. An outline of the kinetics of these systems is given, with the oft-neglected importance of conventional termination being stressed.

scholarly journals Bioengineered airway epithelial grafts with mucociliary function based on collagen IV- and laminin-containing extracellular matrix scaffolds

2020 ◽  
Vol 55 (6) ◽  
pp. 1901200 ◽  
Author(s):  
Nick J.I. Hamilton ◽  
Dani Do Hyang Lee ◽  
Kate H.C. Gowers ◽  
Colin R. Butler ◽  
Elizabeth F. Maughan ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Airway Epithelium ◽  
Airway Epithelial Cell ◽  
Collagen Iv ◽  
Airway Epithelial ◽  
Cell Adherence ◽  
Bronchial Epithelial ◽  
Mucociliary Function

Current methods to replace damaged upper airway epithelium with exogenous cells are limited. Existing strategies use grafts that lack mucociliary function, leading to infection and the retention of secretions and keratin debris. Strategies that regenerate airway epithelium with mucociliary function are clearly desirable and would enable new treatments for complex airway disease.Here, we investigated the influence of the extracellular matrix (ECM) on airway epithelial cell adherence, proliferation and mucociliary function in the context of bioengineered mucosal grafts. In vitro, primary human bronchial epithelial cells (HBECs) adhered most readily to collagen IV. Biological, biomimetic and synthetic scaffolds were compared in terms of their ECM protein content and airway epithelial cell adherence.Collagen IV and laminin were preserved on the surface of decellularised dermis and epithelial cell attachment to decellularised dermis was greater than to the biomimetic or synthetic alternatives tested. Blocking epithelial integrin α2 led to decreased adherence to collagen IV and to decellularised dermis scaffolds. At air–liquid interface (ALI), bronchial epithelial cells cultured on decellularised dermis scaffolds formed a differentiated respiratory epithelium with mucociliary function. Using in vivo chick chorioallantoic membrane (CAM), rabbit airway and immunocompromised mouse models, we showed short-term preservation of the cell layer following transplantation.Our results demonstrate the feasibility of generating HBEC grafts on clinically applicable decellularised dermis scaffolds and identify matrix proteins and integrins important for this process. The long-term survivability of pre-differentiated epithelia and the relative merits of this approach against transplanting basal cells should be assessed further in pre-clinical airway transplantation models.

scholarly journals Antimicrobial Activities and Postantibiotic Effects of Clarithromycin, 14-Hydroxy-Clarithromycin, and Azithromycin in Epithelial Cell Lining Fluid against Clinical Isolates ofHaemophilus influenzae and Streptococcus pneumoniae

1999 ◽  
Vol 43 (5) ◽  
pp. 1291-1293 ◽  
Author(s):  
Kimberly L. Bergman ◽  
Keith M. Olsen ◽  
Tom E. Peddicord ◽  
Paul D. Fey ◽  
Mark E. Rupp
Keyword(s):  
Antimicrobial Activity ◽  
Streptococcus Pneumoniae ◽  
Epithelial Cell ◽  
Haemophilus Influenzae ◽  
Antimicrobial Activities ◽  
Postantibiotic Effect ◽  
Drug Concentrations ◽  
Ofhaemophilus Influenzae ◽  
Cell Lining ◽  
Epithelial Cell Lining

ABSTRACT The antimicrobial activity of concentrations of selected macrolides found in epithelial cell lining fluid was investigated. Clarithromycin demonstrated greater potency and a significantly longer postantibiotic effect (PAE) than azithromycin againstStreptococcus pneumoniae. Azithromycin displayed greater potency, faster killing, and a longer PAE than clarithromycin againstHaemophilus influenzae. Drug concentrations in epithelial cell lining fluid similar to those found in tissue did not improve the synergistic potential of 14-hydroxy-clarithromycin and indicate that a maximal PAE may exist despite increasing concentrations of drug.

scholarly journals Nonacosan-10-ol and n-Alkanes in Leaves of Pinus pinaster

2020 ◽  
Vol 15 (5) ◽  
pp. 1934578X2092607
Author(s):  
Biljana Nikolić ◽  
Marina Todosijević ◽  
Iris Đorđević ◽  
Jovana Stanković ◽  
Zorica S. Mitić ◽  
...  
Keyword(s):  
Chain Length ◽  
Pinus Pinaster ◽  
Cuticular Wax ◽  
Short Chain ◽  
Average Chain Length ◽  
Carbon Preference Index ◽  
Preference Index ◽  
Long Chain

In leaf cuticular wax of Pinus pinaster, content of nonacosan-10-ol is high (77.1% on average). n-Alkanes ranged from C18 to C35 with the most dominant C29 (24.8%). The carbon preference index (CPItotal) ranged from 3.1 to 5.6 (4.0 on average), while the average chain length (ACLtotal) ranged from 14.0 to 17.0 (14.8 on average). Long-chain n-alkanes ( n-C25-35) strongly dominated (80.1%) over middle-chain ( n-C21-24 = 18.9%) and short-chain ( n -C18-20 = 0.9%) n-alkanes.

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