A Laminar-Flow Chamber Assay for Measuring Bacterial Adhesion Under Shear Stress

2011 ◽  
pp. 185-195 ◽  
Author(s):  
Magali Soyer ◽  
Guillaume Duménil
Keyword(s):  
Shear Stress ◽  
Laminar Flow ◽  
Bacterial Adhesion ◽  
Flow Chamber

scholarly journals The influence of shear stress on the adhesion capacity of Legionella pneumophila

2017 ◽  
Vol 68 (2) ◽  
pp. 109-115 ◽  
Author(s):  
Martina Oder ◽  
Rok Fink ◽  
Klemen Bohinc ◽  
Karmen Godič Torkar
Keyword(s):  
Laminar Flow ◽  
Turbulent Flow ◽  
Bacterial Growth ◽  
Legionella Pneumophila ◽  
Bacterial Adhesion ◽  
Flow Chamber ◽  
Bacterial Cells ◽  
Flow Conditions ◽  
Laminar And Turbulent Flow ◽  
Hydrodynamic Effects

Abstract Bacterial adhesion is a complex process influenced by many factors, including hydrodynamic conditions. They affect the transfer of oxygen, nutrients, and bacterial cells in a water supply and cooling systems. The aim of this study was to identify hydrodynamic effects on bacterial adhesion to and detachment from stainless steel surfaces. For this purpose we observed the behaviour of bacterium L. pneumophila in no-flow and laminar and turbulent flow conditions simulated in a fluid flow chamber. The bacterial growth in no-flow and laminar flow conditions was almost identical in the first 24 h, while at 48 and 72 h of incubation, the laminar flow stimulated bacterial growth. In the second part of this study we found that laminar flow accelerated bacterial adhesion in the first 48 h, but after 72 h the amount of bacterial cells exposed to the flow dropped, probably due to detachment. In the third part we found that the turbulent flow detached more bacterial cells than the laminar, which indicates that the strength of shear forces determines the rate of bacterial removal.

scholarly journals Parallel-plate Flow Chamber and Continuous Flow Circuit to Evaluate Endothelial Progenitor Cells under Laminar Flow Shear Stress

10.3791/3349 ◽  
2012 ◽  
Author(s):  
Whitney O. Lane ◽  
Alexandra E. Jantzen ◽  
Tim A. Carlon ◽  
Ryan M. Jamiolkowski ◽  
Justin E. Grenet ◽  
...  
Keyword(s):  
Shear Stress ◽  
Laminar Flow ◽  
Progenitor Cells ◽  
Continuous Flow ◽  
Parallel Plate ◽  
Flow Chamber ◽  
Flow Shear ◽  
Parallel Plate Flow Chamber ◽  
Flow Shear Stress ◽  
Flow Circuit

scholarly journals Shear Stress Induces Change in Extracellular Signal-Regulated Kinase 5 Levels with Sustained Activation under Disturbed and Continuous Laminar Flow

2017 ◽  
Vol 26 (02) ◽  
pp. 109-115 ◽  
Author(s):  
S. Shalaby ◽  
G. Chitragari ◽  
B. Sumpio ◽  
B. Sumpio
Keyword(s):  
Shear Stress ◽  
Laminar Flow ◽  
Vascular Dysfunction ◽  
Flow Chamber ◽  
Flow Conditions ◽  
Extracellular Signal Regulated Kinase ◽  
Glass Slides ◽  
Extracellular Signal ◽  
Endothelial Integrity

AbstractExtracellular signal-regulated kinase 5 (ERK5) has been reported to regulate endothelial integrity and protect from vascular dysfunction under laminar flow. Previously reported research indicates that under laminar flow ERK5 is activated with production of atheroprotective molecules. However, the characterization of ERK5 activation and levels under different flow patterns has not been investigated.Confluent HUVECs were serum-starved then seeded on glass slides. HUVECs incubated in 1% FBS were exposed to continuous laminar flow (CLF), to-and-fro flow (TFF), or pulsatile forward flow (PFF) in a parallel plate flow chamber. At the end of experimentation, cell lysates were immunoblotted with antibodies to phospho-ERK5 and total ERK5. ERK5 activation was assessed by the levels of phosphorylated ERK5. The densitometric mean ± SEM is calculated and analyzed by ANOVA. p < 0.05 is considered significant.Levels of ERK5 decreased with all flow conditions with the largest decrease in TFF flow condition. TFF and CLF exhibited sustained ERK5 phosphorylation in HUVECs stimulated for up to 4 hours. PFF had transient phosphorylation of ERK5 at 2 hours, which then became undetectable at 4 hours of exposure to flow. Also, TFF and CLF both showed decreased levels at 4 hours, suggesting a decrease in activation for these flow conditions.Exposure of HUVEC to different types of shear stress results in varying patterns of activation of ERK5. Activation of ERK5 with TFF suggests a role in the pathogenesis of atherosclerosis and vascular remodeling under disturbed flow conditions.

scholarly journals Kinetic of Adhesion of S. epidermidis with Different EPS Production on Ti6Al4V Surfaces

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Miguel Ángel Pacha-Olivenza ◽  
Abraham Rodríguez-Cano ◽  
M. Luisa González-Martín ◽  
Amparo M. Gallardo-Moreno
Keyword(s):  
Laminar Flow ◽  
Bacterial Adhesion ◽  
Flow Chamber ◽  
Bacterial Suspension ◽  
Order Kinetic ◽  
Adhesion Behavior ◽  
Study Results ◽  
Initial Adhesion ◽  
Controlled Flow ◽  
Flow Devices

Controlling initial bacterial adhesion is essential to prevent biofilm formation and implant-related infection. The search for surface coatings that prevent initial adhesion is a powerful strategy to obtain implants that are more resistant to infection. Tracking the progression of adhesion on surfaces from the beginning of the interaction between bacteria and the surface provides a deeper understanding of the initial adhesion behavior. To this purpose, we have studied the progression over time of bacterial adhesion from a laminar flow of a bacterial suspension, using a modified Robbins device (MRD). Comparing with other laminar flow devices, such as the parallel plate flow chamber, MRD allows the use of diverse substrata under the same controlled flow conditions simultaneously. Two different surfaces of Ti6Al4V and two strains of Staphylococcus epidermidis with different exopolymer production were tested. In addition, the modified Robbins device was examined for its convenience and suitability for the purpose of this study. Results were analyzed according to a pseudofirst order kinetic. The values of the parameters obtained from this model make it possible to discriminate the adhesive behavior of surfaces and bacteria. One of the fitting parameters depends on the bacterial strain and the other only on the surface properties of the substrate.

Design and construction of a linear shear stress flow chamber

1993 ◽  
Vol 21 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Shunichi Usami ◽  
Hsuan-Hsu Chen ◽  
Yihua Zhao ◽  
Shu Chien ◽  
Richard Skalak
Keyword(s):  
Shear Stress ◽  
Flow Chamber ◽  
Linear Shear ◽  
Stress Flow ◽  
Design And Construction

scholarly journals Aging Effect on Structure, Hardness, Roughness Behavior and Bacterial Adhesion on Silver- Palladium Dental Alloy

2020 ◽  
pp. 1-3
Author(s):  
Abu Bakr El-Bediwi ◽  
◽  
Doaa Al- Ragae ◽  
Thoraya El-Helaly ◽  
◽  
...  
Keyword(s):  
Shear Stress ◽  
Bacterial Adhesion ◽  
Maximum Shear Stress ◽  
Aging Effect ◽  
Base Line ◽  
Palladium Alloy ◽  
Dental Alloy ◽  
Roughness Parameters ◽  
Candida Spp ◽  
Silver Palladium

Aging in normal saliva for different interval times make a change in internal structure (Formed phases and started base line) of Sliver- Palladium (Ag-Pd) dental alloy. Also aging in saliva for one, two and three weeks decreased Vickers hardness value, calculated maximum shear stress (τm) and roughness parameters for Sliver- Palladium alloy. Microbiological studies show the Candida spp. stuck on Sliver- Palladium alloy surface and their growth dependent on aging times.

Wall Shear Stress Determination in a Small-Scale Parallel Plate Flow Chamber Using Laser Doppler Velocimetry Under Laminar, Pulsatile and Low-Reynolds Number Turbulent Flows

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Hamed Avari ◽  
Kem A. Rogers ◽  
Eric Savory
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Laser Doppler Velocimetry ◽  
Parallel Plate ◽  
Flow Chamber ◽  
Laser Doppler ◽  
Small Scale ◽  
Doppler Velocimetry ◽  
Flow Conditions ◽  
Parallel Plate Flow Chamber

The parallel plate flow chamber (PPFC) has gained popularity due to its applications in fields such as biological tissue engineering. However, most of the studies using PPFC refer to theoretical relations for estimating the wall shear stress (WSS) and, hence, the accuracy of such quantifications remains elusive for anything other than steady laminar flow. In the current study, a laser Doppler velocimetry (LDV) method was used to quantify the flow in a PPFC (H = 1.8 mm × W = 17.5 mm, Dh = 3.26 mm, aspect ratio = 9.72) under steady Re = 990, laminar pulsatile (carotid Re0-mean = 282 as well as a non-zero-mean sinusoidal Re0-mean = 45 pulse) and low-Re turbulent Re = 2750 flow conditions. A mini-LDV probe was applied, and the absolute location of the LDV measuring volume with the respect to the wall was determined using a signal monitoring technique with uncertainties being around ±27 μm. The uniformity of the flow across the span of the channel, as well as the WSS assessment for all the flow conditions, was measured with the uncertainties all being less than 16%. At least two points within the viscous sublayer of the low-Re turbulent flow were measured (with the y+ for the first point < 3) and the WSS was determined using two methods with the differences between the two methods being within 5%. This paper for the first time presents the experimental determination of WSS using LDV in a small-scale PPFC under various flow conditions, the challenges associated with each condition, and a comparison between the cases. The present data will be useful for those conducting biological or numerical modeling studies using such devices.

Laminar Flow on Endothelial Cells Suppresses eNOS O-GlcNAcylation to Promote eNOS Activity

2021 ◽  
Author(s):  
Sarah Basehore ◽  
Samantha Bohlman ◽  
Callie Weber ◽  
Swathi Swaminathan ◽  
Yuji Zhang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Laminar Flow ◽  
No Production ◽  
Disturbed Flow ◽  
Enos Activity ◽  
Enos Phosphorylation ◽  
Steady Laminar ◽  
In Cells

Rationale: In diabetic animals as well as high glucose cell culture conditions, endothelial nitric oxide synthase (eNOS) is heavily O-GlcNAcylated, which inhibits its phosphorylation and nitric oxide (NO) production. It is unknown, however, whether varied blood flow conditions, which affect eNOS phosphorylation, modulate eNOS activity via O-GlcNAcylation-dependent mechanisms. Objective: The goal of this study was to test if steady laminar flow, but not oscillating disturbed flow, decreases eNOS O-GlcNAcylation, thereby elevating eNOS phosphorylation and NO production. Methods and Results: Human umbilical vein endothelial cells (HUVEC) were exposed to either laminar flow (20 dynes/cm2 shear stress) or oscillating disturbed flow (4{plus minus}6 dynes/cm2 shear stress) for 24 hours in a cone-and-plate device. eNOS O-GlcNAcylation was almost completely abolished in cells exposed to steady laminar but not oscillating disturbed flow. Interestingly, there was no change in protein level or activity of key O-GlcNAcylation enzymes (OGT, OGA, or GFAT). Instead, metabolomics data suggest that steady laminar flow decreases glycolysis and hexosamine biosynthetic pathway (HBP) activity, thereby reducing UDP-GlcNAc pool size and consequent O-GlcNAcylation. Inhibition of glycolysis via 2-deoxy-2-glucose (2-DG) in cells exposed to disturbed flow efficiently decreased eNOS O-GlcNAcylation, thereby increasing eNOS phosphorylation and NO production. Finally, we detected significantly higher O-GlcNAcylated proteins in endothelium of the inner aortic arch in mice, suggesting that disturbed flow increases protein O-GlcNAcylation in vivo. Conclusions: Our data demonstrate that steady laminar but not oscillating disturbed flow decreases eNOS O-GlcNAcylation by limiting glycolysis and UDP-GlcNAc substrate availability, thus enhancing eNOS phosphorylation and NO production. This research shows for the first time that O-GlcNAcylation is regulated by mechanical stimuli, relates flow-induced glycolytic reductions to macrovascular disease, and highlights targeting HBP metabolic enzymes in endothelial cells as a novel therapeutic strategy to restore eNOS activity and prevent EC dysfunction in cardiovascular disease.

Invited Review: Effects of flow on vascular endothelial intracellular calcium signaling of rat aortas ex vivo

2000 ◽  
Vol 89 (4) ◽  
pp. 1657-1662 ◽  
Author(s):  
Chauying J. Jen ◽  
Shuo-Ju Jhiang ◽  
Hsiun-Ing Chen
Keyword(s):  
Shear Stress ◽  
Intracellular Calcium ◽  
Calcium Influx ◽  
Ex Vivo ◽  
Flow Chamber ◽  
Shear Stresses ◽  
Dependent Manner ◽  
Intracellular Calcium Signaling ◽  
Flow Effects ◽  
Dose Dependent

To study the effects of flow on in situ endothelial intracellular calcium concentration ([Ca2+]i) signaling, rat aortic rings were loaded with fura 2, mounted on a tissue flow chamber, and divided into control and flow-pretreated groups. The latter was perfused with buffer at a shear stress of 50 dyns/cm2 for 1 h. Endothelial [Ca2+]i responses to ACh or shear stresses were determined by ratio image analysis. Moreover, ACh-induced [Ca2+]i elevation responses were measured in a calcium-free buffer, or in the presence of SKF-96365, to elucidate the role of calcium influx in the flow effects. Our results showed that 1) ACh increased endothelial [Ca2+]i in a dose-dependent manner, and these responses were incremented by flow-pretreatment; 2) the differences in ACh-induced [Ca2+]i elevation between control and flow-pretreated groups were abolished by SKF-96365 or by Ca2+-free buffer; and 3) in the presence of 10−5 M ATP, shear stress induced dose-dependent [Ca2+]i elevation responses that were not altered by flow-pretreatment. In conclusion, flow-pretreatment augments the ACh-induced endothelial calcium influx in rat aortas ex vivo.

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