scholarly journals An in vitro study on factors affecting endotoxin neutralization in human plasma using the Limulus amebocyte lysate test

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Stephan Harm ◽  
Claudia Schildböck ◽  
Karin Strobl ◽  
Jens Hartmann
Keyword(s):  
Human Plasma ◽  
Human Blood ◽  
Divalent Cations ◽  
In Vitro Study ◽  
Serum Levels ◽  
Content Type ◽  
Factors Affecting ◽  
Endotoxin Activity ◽  
The Individual

AbstractEndotoxin neutralization, caused by plasma components, makes it difficult to detect endotoxins in human blood. In this study, we investigated which factors influence the recovery of endotoxins using limulus ameobocyte lysate (LAL)-based assays. The individual factors that were examined in more detail were lipoprotein content, type of blood anticoagulation, kinetics and serum levels of divalent cations. Furthermore, it was investigated whether there is a direct correlation between LAL activity and monocyte activation. We could show that polyanionic heparin increases endotoxin recovery in blood, while citrate anticoagulation promotes endotoxin neutralization. Furthermore, we could show that the endotoxin activity in human plasma and serum decreases strongly over time. Time-dependent endotoxin neutralization reaches its maximum after 4–6 h incubation. By means of filtration tests we could determine that endotoxins in the plasma bind to lipoproteins but do not influence their activity. Comparative measurements have shown that high LAL activity of endotoxins in plasma simultaneously possesses high monocyte activating properties in whole blood. For the maximum recovery of endotoxins in human blood the physiological calcium and magnesium concentrations are sufficient. In this study, it was shown that the endotoxin neutralizing plasma components have a molecular weight similar to β2-microglobulin (11.7 kDa). For the exact identification of the endotoxin neutralizing plasma components, which caused a modulation of the immunostimulating endotoxin activity, further investigations have to be carried out in the future.

scholarly journals In VitroAnalyses of the Effects of Heparin and Parabens on Candida albicans Biofilms and Planktonic Cells

2011 ◽  
Vol 56 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Marisa H. Miceli ◽  
Stella M. Bernardo ◽  
T. S. Neil Ku ◽  
Carla Walraven ◽  
Samuel A. Lee
Keyword(s):  
Candida Albicans ◽  
Metabolic Activity ◽  
Biofilm Formation ◽  
High Dose ◽  
Dependent Manner ◽  
Planktonic Cells ◽  
Content Type ◽  
Heparin Sodium ◽  
The Individual

ABSTRACTInfections and thromboses are the most common complications associated with central venous catheters. Suggested strategies for prevention and management of these complications include the use of heparin-coated catheters, heparin locks, and antimicrobial lock therapy. However, the effects of heparin onCandida albicansbiofilms and planktonic cells have not been previously studied. Therefore, we sought to determine thein vitroeffect of a heparin sodium preparation (HP) on biofilms and planktonic cells ofC. albicans. Because HP contains two preservatives, methyl paraben (MP) and propyl paraben (PP), these compounds and heparin sodium without preservatives (Pure-H) were also tested individually. The metabolic activity of the mature biofilm after treatment was assessed using XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction and microscopy. Pure-H, MP, and PP caused up to 75, 85, and 60% reductions of metabolic activity of the mature preformedC. albicansbiofilms, respectively. Maximal efficacy against the mature biofilm was observed with HP (up to 90%) compared to the individual compounds (P< 0.0001). Pure-H, MP, and PP each inhibitedC. albicansbiofilm formation up to 90%. A complete inhibition of biofilm formation was observed with HP at 5,000 U/ml and higher. When tested against planktonic cells, each compound inhibited growth in a dose-dependent manner. These data indicated that HP, MP, PP, and Pure-H havein vitroantifungal activity againstC. albicansmature biofilms, formation of biofilms, and planktonic cells. Investigation of high-dose heparin-based strategies (e.g., heparin locks) in combination with traditional antifungal agents for the treatment and/or prevention ofC. albicansbiofilms is warranted.

scholarly journals In vitro factors affecting the concentration of gamma-LpE (γ-LpE) in human plasma

1998 ◽  
Vol 39 (4) ◽  
pp. 861-872 ◽  
Author(s):  
Larbi Krimbou ◽  
Michel Tremblay ◽  
Hélène Jacques ◽  
Jean Davignon ◽  
Jeffrey S. Cohn
Keyword(s):  
Human Plasma ◽  
Factors Affecting

Factors Affecting the Cement Penetration of a Hip Resurfacing Implant: An in Vitro Study

2006 ◽  
Vol 16 (4_suppl) ◽  
pp. 82-89 ◽  
Author(s):  
R. Howald ◽  
U. Kesteris ◽  
R. Klabunde ◽  
J. Krevolin
Keyword(s):  
In Vitro Study ◽  
Hip Resurfacing ◽  
Vitro Study ◽  
Factors Affecting ◽  
Cement Penetration

Environment in the lung of cystic fibrosis patients stimulates the expression of biofilm phenotype in Mycobacterium abscessus

2022 ◽  
Vol 71 (1) ◽  
Author(s):  
Bailey F. Keefe ◽  
Luiz E. Bermudez
Keyword(s):  
Cystic Fibrosis ◽  
Host Cell ◽  
Biofilm Formation ◽  
Type Species ◽  
Divalent Cations ◽  
Mycobacterium Abscessus ◽  
Content Type ◽  
Link Type ◽  
Populations At Risk

Introduction. Pulmonary infections caused by organisms of the Mycobacterium abscessus complex are increasingly prevalent in populations at risk, such as patients with cystic fibrosis, bronchiectasis and emphysema. Hypothesis. M. abscessus infection of the lung is not observed in immunocompetent individuals, which raises the possibility that the compromised lung environment is a suitable niche for the pathogen to thrive in due to the overproduction of mucus and high amounts of host cell lysis. Aim. Evaluate the ability of M. abscessus to form biofilm and grow utilizing in vitro conditions as seen in immunocompromised lungs of patients. Methodology. We compared biofilm formation and protein composition in the presence and absence of synthetic cystic fibrosis medium (SCFM) and evaluated the bacterial growth when exposed to human DNA. Results. M. abscessus is capable of forming biofilm in SCFM. By eliminating single components found in the medium, it became clear that magnesium works as a signal for the biofilm formation, and chelation of the divalent cations resulted in the suppression of biofilm formation. Investigation of the specific proteins expressed in the presence of SCFM and in the presence of SCFM lacking magnesium revealed many different proteins between the conditions. M. abscessus also exhibited growth in SCFM and in the presence of host cell DNA, although the mechanism of DNA utilization remains unclear. Conclusions. In vitro conditions mimicking the airways of patients with cystic fibrosis appear to facilitate M. abscessus establishment of infection, and elimination of magnesium from the environment may affect the ability of the pathogen to establish infection.

Organizational dynamics: exploring the factors affecting knowledge sharing behavior

Kybernetes ◽  
2019 ◽  
Vol 49 (1) ◽  
pp. 165-181 ◽  
Author(s):  
Nóra Obermayer ◽  
Viktoria Erika Toth
Keyword(s):  
Knowledge Sharing ◽  
Organizational Factors ◽  
Organizational Characteristics ◽  
Organizational Dynamics ◽  
Quantitative Methodology ◽  
Data Set ◽  
Content Type ◽  
Factors Affecting ◽  
Effective Manner ◽  
The Individual

Purpose The purpose of this study is to identify the individual and organizational factors that influence knowledge sharing (KS) behavior within Hungarian organizations. Design/methodology/approach The data were obtained from 238 completed questionnaires collected via the LimeSurvey system. The analysis is based on applied quantitative methodology, both descriptive and inferential statistics were used. The research investigated the relationships between individual and organizational characteristics and the KS behavior at individual and global levels. Findings Among individual factors, significant relationships have been identified regarding the generation and position of individuals, and KS behavior, while gender and education do not seem to play a significant role. With respect to organizational factors, the size of the organization and the tenure of individuals are found to be significant. Research limitations/implications The results of the analysis are limited because the data set was not large enough to investigate inter- and intra-industry variability. Practical implications The outcome of this research can support the design of managerial and organizational processes and incentives that will potentially facilitate KS in a more efficient and effective manner. Such improved KS is likely to improve the overall performance of knowledge-intensive organizations. Originality/value The original value of this research is that individual and organizational characteristics have been identified that influence KS behavior. The study focuses on a single country, Hungary, and provides relevant insight into the organizational dynamics of a specific national context.

scholarly journals Measurement of Immunoreactive Angiotensin-(1–7) Heptapeptide in Human Blood

2001 ◽  
Vol 47 (4) ◽  
pp. 726-729 ◽  
Author(s):  
Juerg Nussberger ◽  
Dorette B Brunner ◽  
Juerg A Nyfeler ◽  
Lilly Linder ◽  
Hans R Brunner
Keyword(s):  
Detection Limit ◽  
Human Plasma ◽  
Human Blood ◽  
Plasma Concentrations ◽  
Specific Antiserum ◽  
Clinical Settings ◽  
Physiological Effects ◽  
Reliable Measurement ◽  
Blood Concentrations

Abstract Background: The renal enzyme renin cleaves from the hepatic α2-globulin angiotensinogen angiotensin-(1–10) decapeptide [Ang-(1–10)], which is further metabolized to smaller peptides that help maintain cardiovascular homeostasis. The Ang-(1–7) heptapeptide has been reported to have several physiological effects, including natriuresis, diuresis, vasodilation, and release of vasopressin and prostaglandins. Methods: To investigate Ang-(1–7) in clinical settings, we developed a method to measure immunoreactive (ir-) Ang-(1–7) in 2 mL of human blood and to estimate plasma concentrations by correcting for the hematocrit. A sensitive and specific antiserum against Ang-(1–7) was raised in a rabbit. Human blood was collected in the presence of an inhibitor mixture including a renin inhibitor to prevent peptide generation in vitro. Ang-(1–7) was extracted into ethanol and purified on phenylsilylsilica. The peptide was quantified by radioimmunoassay. Increasing doses of Ang-(1–7) were infused into volunteers, and plasma concentrations of the peptide were measured. Results: The detection limit for plasma ir-Ang-(1–7) was 1 pmol/L. CVs for high and low blood concentrations were 4% and 20%, respectively, and between-assay CVs were 8% and 13%, respectively. Reference values for human plasma concentrations of ir-Ang-(1–7) were 1.0–9.5 pmol/L (median, 4.7 pmol/L) and increased linearly during infusion of increasing doses of Ang-(1–7). Conclusions: Reliable measurement of plasma ir-Ang-(1–7) is achieved with efficient inhibition of enzymes that generate or metabolize Ang-(1–7) after blood sampling, extraction in ethanol, and purification on phenylsilylsilica, and by use of a specific antiserum.

scholarly journals In Vitro Study of Stepwise Acquisition of rv0678 and atpE Mutations Conferring Bedaquiline Resistance

2019 ◽  
Vol 63 (8) ◽  
Author(s):  
Nabila Ismail ◽  
Nazir A. Ismail ◽  
Shaheed V. Omar ◽  
Remco P. H. Peters
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Solid Medium ◽  
In Vitro Study ◽  
Whole Genome ◽  
Content Type ◽  
Phenotypic Resistance ◽  
Atcc Strain ◽  
High Level ◽  
Level Resistance

ABSTRACT Bedaquiline resistance within Mycobacterium tuberculosis may arise through efflux-based (rv0678) or target-based (atpE) pathway mutations. M. tuberculosis mutant populations from each of five sequential steps in a passaging approach, using a pyrazinamide-resistant ATCC strain, were subjected to MIC determinations and whole-genome sequencing. Exposure to increasing bedaquiline concentrations resulted in increasing phenotypic resistance (up to >2 μg/ml) through MIC determination on solid medium (Middlebrook 7H10). rv0678 mutations were dynamic, while atpE mutations were fixed, once occurring. We present the following hypothesis for in vitro emergence of bedaquiline resistance: rv0678 mutations may be the first transient step in low-level resistance acquisition, followed by high-level resistance due to fixed atpE mutations.

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