scholarly journals In vivoadhesion force measurements ofChlamydomonason model substrates

Soft Matter ◽  
2019 ◽  
Vol 15 (14) ◽  
pp. 3027-3035 ◽  
Author(s):  
Christian Titus Kreis ◽  
Alice Grangier ◽  
Oliver Bäumchen
Keyword(s):  
Adhesion Force ◽  
Force Measurements ◽  
Adhesion Mechanism ◽  
Abiotic Surfaces

A universal adhesion mechanism allowsChlamydomonasto effectively colonize abiotic surfaces, as evidenced byin vivoadhesion force measurements.

Integrin-like RGD-dependent cell adhesion mechanism is involved in the rapid killing of Onchocerca microfilariae during early infection of Simulium damnosum s.l.

Parasitology ◽  
2001 ◽  
Vol 122 (4) ◽  
pp. 433-438 ◽  
Author(s):  
H. E. HAGEN ◽  
S. L. KLÄGER
Keyword(s):  
Cell Adhesion ◽  
Intermediate Host ◽  
Blocking Agent ◽  
Early Infection ◽  
Adhesion Mechanism ◽  
Simulium Damnosum ◽  
Dependent Cell ◽  
Species Specific

Injection trials with compatible and non-compatible Onchocerca species into S. damnosum s.l., the vector of human and bovine onchocerciasis, demonstrated that the rapid killing of microfilariae within the blackfly's haemocoel is species specific. In the presence of the peptide RGDS as a blocking agent for integrin-like receptors of haemocytes, the survival of O. ochengi microfilariae in its natural intermediate host was significantly increased. This increased survival 24 h p.i. correlated with a significant decrease of apoptosis levels in the microfilariae following a 2 h exposure to the haemolymph in vivo. These findings suggest that haemocytes are directly involved in the killing of Onchocerca microfilariae in the blackfly.

Accuracy of Orthodontic Force and Tooth Movement Measurements

1996 ◽  
Vol 23 (3) ◽  
pp. 241-248 ◽  
Author(s):  
Dan Lundgren ◽  
Py Owman-Moll ◽  
Jüri Kurol ◽  
Birgit Mårtensson
Keyword(s):  
Tooth Movement ◽  
Mean Value ◽  
Measurement Methods ◽  
Calibration Data ◽  
Force Measurements ◽  
Accuracy Of Measurement ◽  
Measuring Machine ◽  
Initial Force ◽  
Level Of Agreement

This study was designed to test the accuracy of measurement methods for assessment of force and tooth movement in orthodontic procedures. Daily in vivo measurements of the force produced by activated archwires showed that the initial force declined substantially (by 20 per cent of mean value) within 3 days. Both the ‘trueness’ (validity) and precision of the force measurements, obtained with a strain gauge, were found to be high (SD values were 1·0 cN and 0·4 cN, respectively). Horizontal tooth movements were measured with three different instruments: a slide calliper, a co-ordinate measuring machine, and laser measuring equipment based on holograms. There was a good level of agreement between these methods. This was also confirmed by calibration data. The precision of the methods was (SD values) 0·06, 0·07, and 0·13 mm, respectively. The benefits of the use of the co-ordinate measuring machine are obvious, since it can measure tooth movements in relation to reference planes in all directions.

scholarly journals An optimised GAS-pharyngeal cell biofilm model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Heema K. N. Vyas ◽  
Jason D. McArthur ◽  
Martina L. Sanderson-Smith
Keyword(s):  
Crystal Violet ◽  
Biofilm Formation ◽  
Cell Model ◽  
Matrix Material ◽  
Three Dimensional ◽  
Growth Period ◽  
Optimal Growth ◽  
Abiotic Surfaces

AbstractGroup A Streptococcus (GAS) causes 700 million infections and accounts for half a million deaths per year. Biofilm formation has been implicated in both pharyngeal and dermal GAS infections. In vitro, plate-based assays have shown that several GAS M-types form biofilms, and multiple GAS virulence factors have been linked to biofilm formation. Although the contributions of these plate-based studies have been valuable, most have failed to mimic the host environment, with many studies utilising abiotic surfaces. GAS is a human specific pathogen, and colonisation and subsequent biofilm formation is likely facilitated by distinct interactions with host tissue surfaces. As such, a host cell-GAS model has been optimised to support and grow GAS biofilms of a variety of GAS M-types. Improvements and adjustments to the crystal violet biofilm biomass assay have also been tailored to reproducibly detect delicate GAS biofilms. We propose 72 h as an optimal growth period for yielding detectable biofilm biomass. GAS biofilms formed are robust and durable, and can be reproducibly assessed via staining/washing intensive assays such as crystal violet with the aid of methanol fixation prior to staining. Lastly, SEM imaging of GAS biofilms formed by this model revealed GAS cocci chains arranged into three-dimensional aggregated structures with EPS matrix material. Taken together, we outline an efficacious GAS biofilm pharyngeal cell model that can support long-term GAS biofilm formation, with biofilms formed closely resembling those seen in vivo.

scholarly journals Hemodynamic forces can be accurately measured in vivo with optical tweezers

2017 ◽  
Author(s):  
Sébastien Harlepp ◽  
Fabrice Thalmann ◽  
Gautier Follain ◽  
Jacky G. Goetz
Keyword(s):  
Optical Tweezers ◽  
Cell Biology ◽  
Accurate Determination ◽  
Force Measurements ◽  
Hemodynamic Forces ◽  
Non Invasive ◽  
Drag Forces ◽  
Measured Flow ◽  
Living Organisms

AbstractForce sensing and generation at the tissular and cellular scale is central to many biological events. There is a growing interest in modern cell biology for methods enabling force measurements in vivo. Optical trapping allows non-invasive probing of pico-Newton forces and thus emerged as a promising mean for assessing biomechanics in vivo. Nevertheless, the main obstacles rely in the accurate determination of the trap stiffness in heterogeneous living organisms, at any position where the trap is used. A proper calibration of the trap stiffness is thus required for performing accurate and reliable force measurements in vivo. Here, we introduce a method that overcomes these difficulties by accurately measuring hemodynamic profiles in order to calibrate the trap stiffness. Doing so, and using numerical methods to assess the accuracy of the experimental data, we measured flow profiles and drag forces imposed to trapped red blood cells of living zebrafish embryos. Using treatments enabling blood flow tuning, we demonstrated that such method is powerful in measuring hemodynamic forces in vivo with accuracy and confidence. Altogether, this study demonstrates the power of optical tweezing in measuring low range hemodynamic forces in vivo and offers an unprecedented tool in both cell and developmental biology.

scholarly journals Rational design of protein-specific folding modifiers

2020 ◽  
Author(s):  
Anirban Das ◽  
Anju Yadav ◽  
Mona Gupta ◽  
R Purushotham ◽  
Vishram L. Terse ◽  
...  
Keyword(s):  
Single Molecule ◽  
Rational Design ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Force Measurements ◽  
Folding Nucleus ◽  
Dynamics Simulations ◽  
General Method

AbstractProtein folding can go wrong in vivo and in vitro, with significant consequences for the living cell and the pharmaceutical industry, respectively. Here we propose a general design principle for constructing small peptide-based protein-specific folding modifiers. We construct a ‘xenonucleus’, which is a pre-folded peptide that resembles the folding nucleus of a protein, and demonstrate its activity on the folding of ubiquitin. Using stopped-flow kinetics, NMR spectroscopy, Förster Resonance Energy transfer, single-molecule force measurements, and molecular dynamics simulations, we show that the ubiquitin xenonucleus can act as an effective decoy for the native folding nucleus. It can make the refolding faster by 33 ± 5% at 3 M GdnHCl. In principle, our approach provides a general method for constructing specific, genetically encodable, folding modifiers for any protein which has a well-defined contiguous folding nucleus.

Surface diagnostics for scale analysis

2004 ◽  
Vol 49 (2) ◽  
pp. 183-190 ◽  
Author(s):  
S. Dunn ◽  
S. Impey ◽  
C. Kimpton ◽  
S.A. Parsons ◽  
J. Doyle ◽  
...  
Keyword(s):  
Adhesion Force ◽  
Polymer Materials ◽  
Rapid Screening ◽  
Force Measurements ◽  
Energy Materials ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Modified ◽  
Surface Diagnostics ◽  
Microscopy Techniques

Stainless steel, polymethylmethacrylate and polytetrafluoroethylene coupons were analysed for surface topographical and adhesion force characteristics using tapping mode atomic force microscopy and force-distance microscopy techniques. The two polymer materials were surface modified by polishing with silicon carbide papers of known grade. The struvite scaling rate was determined for each coupon and related to the data gained from the surface analysis. The scaling rate correlated well with adhesion force measurements indicating that lower energy materials scale at a lower rate. The techniques outlined in the paper provide a method for the rapid screening of materials in potential scaling applications.

scholarly journals Non-surface Attached Bacterial Aggregates: A Ubiquitous Third Lifestyle

2020 ◽  
Vol 11 ◽  
Author(s):  
Yu-Ming Cai
Keyword(s):  
Ex Vivo ◽  
Large River ◽  
Formation Mechanisms ◽  
Clinical Settings ◽  
Standard Type ◽  
Technical Developments ◽  
Abiotic Surfaces ◽  
Bacterial Aggregates ◽  
Type Strains

Bacteria are now generally believed to adopt two main lifestyles: planktonic individuals, or surface-attached biofilms. However, in recent years medical microbiologists started to stress that suspended bacterial aggregates are a major form of bacterial communities in chronic infection sites. Despite sharing many similarities with surface-attached biofilms and are thus generally defined as biofilm-like aggregates, these non-attached clumps of cells in vivo show much smaller sizes and different formation mechanisms. Furthermore, ex vivo clinical isolates were frequently reported to be less attached to abiotic surfaces when compared to standard type strains. While this third lifestyle is starting to draw heavy attention in clinical studies, it has a long history in natural and environmental sciences. For example, marine gel particles formed by bacteria attachment to phytoplankton exopolymers have been well documented in oceans; large river and lake snows loaded with bacterial aggregates are frequently found in freshwater systems; multispecies bacterial “flocs” have long been used in wastewater treatment. This review focuses on non-attached aggregates found in a variety of natural and clinical settings, as well as some recent technical developments facilitating aggregate research. The aim is to summarise the characteristics of different types of bacterial aggregates, bridging the knowledge gap, provoking new perspectives for researchers from different fields, and highlighting the importance of more research input in this third lifestyle of bacteria closely relevant to our daily life.

Nanoscale Analysis of Surface Topography and Adhesion Force Measurements of Flagella Isolated from Chlamydomonas reinhardtii

2013 ◽  
Vol 8 (3) ◽  
pp. 163-170 ◽  
Author(s):  
Shivaraman Ramaswamy ◽  
Dhananjay Suresh ◽  
Harsha Bathula ◽  
Ojas Mahapatra ◽  
Kantha D. Arunachalam ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Surface Topography ◽  
Adhesion Force ◽  
Force Measurements
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