scholarly journals Biophysical characterization reveals the similarities of liposomes produced using microfluidics and electroformation

2019 ◽  
Author(s):  
Michael Schaich ◽  
Diana Sobota ◽  
Hannah Sleath ◽  
Jehangir Cama ◽  
Ulrich F. Keyser
Keyword(s):  
Diffusion Coefficients ◽  
Lipid Membranes ◽  
Fluorescence Recovery After Photobleaching ◽  
Lateral Diffusion ◽  
Experimental Conditions ◽  
Biophysical Characterization ◽  
Lipid Mixtures ◽  
Significant Interest ◽  
Versatile Tool

AbstractGiant Unilamellar Vesicles (GUVs) are a versatile tool in many branches of science, including biophysics and synthetic biology. Octanol-Assisted Liposome Assembly (OLA), a recently developed microfluidic technique enables the production and testing of GUVs within a single device under highly controlled experimental conditions. It is therefore gaining significant interest as a platform for use in drug discovery, the production of artificial cells and more generally for controlled studies of the properties of lipid membranes. In this work, we expand the capabilities of the OLA technique by forming GUVs of tunable binary lipid mixtures of DOPC, DOPG and DOPE. Using fluorescence recovery after photobleaching we investigated the lateral diffusion coefficients of lipids in OLA liposomes and found the expected values in the range of 1 μm2/s for the lipid systems tested. We studied the OLA derived GUVs under a range of conditions and compared the results with electroformed vesicles. Overall, we found the lateral diffusion coefficients of lipids in vesicles obtained with OLA to be quantitatively similar to those in vesicles obtained via traditional electroformation. Our results provide a quantitative biophysical validation of the quality of OLA derived GUVs, which will facilitate the wider use of this versatile platform.

scholarly journals Defining the Diffusion in Model Membranes Using Line Fluorescence Recovery after Photobleaching

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 434
Author(s):  
Jakob L. Kure ◽  
Camilla B. Andersen ◽  
Thomas E. Rasmussen ◽  
B. Christoffer Lagerholm ◽  
Eva C. Arnspang
Keyword(s):  
Diffusion Coefficient ◽  
Lipid Membranes ◽  
Fluorescence Recovery After Photobleaching ◽  
Plasma Membranes ◽  
Simple Technique ◽  
Membrane Lipids ◽  
Model Membranes ◽  
Fluorescence Recovery ◽  
Synthetic Membranes ◽  
Lipid Mixtures

In this study, we explore the use of line FRAP to detect diffusion in synthetic lipid membranes. The study of the dynamics of these membrane lipids can, however, be challenging. The diffusion in two different synthetic membranes consisting of the lipid mixtures 1:1 DOPC:DPPC and 2:2:1 DOPC:DPPC:Cholesterol was studied with line FRAP. A correlation between diffusion coefficient and temperature was found to be dependent on the morphology of the membrane. We suggest line FRAP as a promising accessible and simple technique to study diffusion in plasma membranes.

A Critical Review of Morphologic Findings and Data From 14 Toxicological Studies Involving Fish Exposures to Diclofenac

2021 ◽  
pp. 019262332198965
Author(s):  
Jeffrey C. Wolf
Keyword(s):  
Diagnostic Errors ◽  
Data Interpretation ◽  
Included Study ◽  
Experimental Conditions ◽  
Regulatory Decision ◽  
Transmission Electron ◽  
Toxicological Studies ◽  
Morphologic Data ◽  
Ambiguous Data

A number of studies have investigated the potential toxicity of the analgesic agent diclofenac (DCF) in various fish species under a diverse array of experimental conditions. Reported evidence of toxicity in these investigations is often strongly reliant on morphologic end points such as histopathology, immunohistochemistry, and transmission electron microscopy. However, it may be challenging for scientists who perform environmental hazard or risk determination to fully appreciate the intricacies of these specialized endpoints. Therefore, the purpose of the current review was to critically assess the quality of morphologic data in 14 papers that described the experimental exposure of fish to DCF. Areas of focus during this review included study design, diagnostic accuracy, magnitude of reported changes, data interpretation and presentation, and the credibility of individual reported findings. Positive attributes of some studies included robust experimental designs, accurate diagnoses, and straightforward and transparent data reporting. Issues identified in certain articles included diagnostic errors, failure to account for sampling and/or observer bias, failure to evaluate findings according to sex, exaggeration of lesion severity, interstudy inconsistencies, unexplained phenomena, and incomplete or ambiguous data presentation. It is hoped that the outcome of this review will be of value for personnel involved in regulatory decision-making.

A new approach based on graph matching and evolutionary approach for sport scheduling problem

2020 ◽  
pp. 1-16
Author(s):  
Meriem Khelifa ◽  
Dalila Boughaci ◽  
Esma Aïmeur
Keyword(s):  
Graph Matching ◽  
State Of The Art ◽  
Travel Cost ◽  
Round Robin ◽  
New Approach ◽  
Traveling Tournament Problem ◽  
Significant Interest ◽  
National League ◽  
Better Than

The Traveling Tournament Problem (TTP) is concerned with finding a double round-robin tournament schedule that minimizes the total distances traveled by the teams. It has attracted significant interest recently since a favorable TTP schedule can result in significant savings for the league. This paper proposes an original evolutionary algorithm for TTP. We first propose a quick and effective constructive algorithm to construct a Double Round Robin Tournament (DRRT) schedule with low travel cost. We then describe an enhanced genetic algorithm with a new crossover operator to improve the travel cost of the generated schedules. A new heuristic for ordering efficiently the scheduled rounds is also proposed. The latter leads to significant enhancement in the quality of the schedules. The overall method is evaluated on publicly available standard benchmarks and compared with other techniques for TTP and UTTP (Unconstrained Traveling Tournament Problem). The computational experiment shows that the proposed approach could build very good solutions comparable to other state-of-the-art approaches or better than the current best solutions on UTTP. Further, our method provides new valuable solutions to some unsolved UTTP instances and outperforms prior methods for all US National League (NL) instances.

Lateral Mobility of Integrin αIIbβ3 (Glycoprotein IIb/IIIa) in the Plasma Membrane of a Human Megakaryocyte

1997 ◽  
Vol 77 (01) ◽  
pp. 143-149 ◽  
Author(s):  
Annelies Schootemeijer ◽  
Gijsbert van Willigen ◽  
Hans van der Vuurst ◽  
Leon G J Tertoolen ◽  
Siegfried W De Laat ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Fluorescence Recovery After Photobleaching ◽  
Cell Activation ◽  
Lateral Diffusion ◽  
Cytochalasin D ◽  
Lag Phase ◽  
Integrin Αiibβ3 ◽  
Cell Matrix ◽  
Cytoplasmic Actin ◽  
Mobile Fraction

SummaryThe migration of integrins to sites of cell-cell and cell-matrix contact is thought to be important for adhesion strengthening. We studied the lateral diffusion of integrin αIIbβ3 (glycoprotein Ilb/IIIa) in the plasma membrane of a cultured human megakaryocyte by fluorescence recovery after photobleaching of FITC-labelled monovalent Fab fragments directed against the P3 subunit. The diffusion of P3 on the unstimulated megakaryocyte showed a lateral diffusion coefficient (D) of 0.37 X10'9 cm2/s and a mobile fraction of about 50%. Stimulation with ADP (20 μM) or α-thrombin (10 U/ml) at 22° C induced transient decreases in both parameters reducing D to 0.21 X 10‘9 cm2/s and the mobile fraction to about 25%. The fall in D was observed within 1 min after stimulation but the fall in mobile fraction showed a lag phase of 5 min. The lag phase was absent in the presence of Calpain I inhibitor, whereas cytochalasin D completely abolished the decrease in mobile fraction. The data are compatible with the concept that cell activation induces anchorage of 50% of the mobile αIIbβ3 (25% of the whole population of receptor) to the cytoplasmic actin filaments, although, as discussed, other rationals are not ruled out.

An Examination of Language Samples Obtained under Three Experimental Conditions

1982 ◽  
Vol 13 (2) ◽  
pp. 121-128 ◽  
Author(s):  
Louise D. Stalnaker ◽  
Nancy A. Creaghead
Keyword(s):  
Preschool Children ◽  
Head Start ◽  
Experimental Conditions ◽  
Semantic Relationships ◽  
Three Samples ◽  
The Mean ◽  
Mean Length Of Utterance ◽  
Language Sample

Language samples were obtained from 12 Head Start preschool children under the following three experimental conditions: Condition I, Retelling a Story with Toys; Condition II, Playing with Toys; Condition III, Toys with Questions. The quantity and quality of the three samples gathered from each child were compared by analyzing the total number of utterances, the proportion of the total utterances which were sentence fragments, the number of transformations and adverbial expansions, the number of different semantic relationships, and the mean length of utterance (MLU). Results indicated that retelling a story produced the largest MLU, but toys and questions produced more utterances. These findings indicated that questioning children does not inhibit their language and asking them to retell a story may be a fruitful approach to use when gathering a language sample.

scholarly journals Lateral diffusion of wild-type and mutant Ld antigens in L cells.

1984 ◽  
Vol 99 (6) ◽  
pp. 2333-2335 ◽  
Author(s):  
M Edidin ◽  
M Zuniga
Keyword(s):  
Plasma Membrane ◽  
Diffusion Coefficients ◽  
Transmembrane Protein ◽  
Transmembrane Proteins ◽  
Lateral Diffusion ◽  
Cytoplasmic Domain ◽  
Histocompatibility Antigen ◽  
Wild Type ◽  
Major Histocompatibility Antigen ◽  
Cytoplasmic Side

We have compared the lateral diffusion of intact transmembrane proteins, wild-type H-2Ld antigens, with that of mutants truncated in the cytoplasmic domain. Diffusion coefficients and mobile fractions were similar for all molecules examined, from wild-type Ld antigens with 31 residues on the cytoplasmic side of the plasma membrane to mutants with only four residues in the cytoplasmic domain. This result limits ways in which the lateral diffusion of a major histocompatibility antigen, a transmembrane protein, can be constrained by interactions with other molecules.

Using the CL-770 Spectrophotometer to Quantify Serum Immunoglobulins

1993 ◽  
Vol 74 (3) ◽  
pp. 232-233
Author(s):  
E. E. Krasnoshchekova ◽  
K. T. Valeeva
Keyword(s):  
Calibration Graph ◽  
Experimental Conditions ◽  
Serum Immunoglobulins ◽  
Monospecific Antiserum ◽  
Agar Layer

Serum immunoglobulins (A, G, M) are usually quantified by radial gel immunodiffusion (RID). It is based on measuring the diameter of the precipitation ring formed when the serum is added to the wells cut out in the agar layer in which the monospecific antiserum is preliminarily dispersed. The gel plates are placed in a humid chamber for 24-48 hours. At the end of the incubation, the diameter of the precipitation ring is measured. Under standard experimental conditions, the diameter of the precipitation ring is directly proportional to the concentration of the studied immunoglobulin. The amount of immunoglobulins is determined by constructing a calibration graph. The results of determining the concentration of serum immunoglobulins by the RID method are issued only on the 3rd day of the study. Clinicians are not always satisfied with the timing of the results and the quality of the study, since the latter depends on many factors - thoroughness (conducting the experiment, the quality and thickness of the gel, the scale of the schedule, etc.)

scholarly journals Assessment of neuropsychiatric symptoms in dementia: Toward improving accuracy

2013 ◽  
Vol 7 (3) ◽  
pp. 244-251 ◽  
Author(s):  
Florindo Stella
Keyword(s):  
Rating Scale ◽  
High Reliability ◽  
Neuropsychiatric Symptoms ◽  
Clinical Approach ◽  
Behavioral Disturbances ◽  
Versatile Tool ◽  
Clinician Rating ◽  
Improving Accuracy ◽  
Elderly Caregivers

ABSTRACT The issue of this article concerned the discussion about tools frequently used tools for assessing neuropsychiatric symptoms of patients with dementia, particularly Alzheimer's disease. The aims were to discuss the main tools for evaluating behavioral disturbances, and particularly the accuracy of the Neuropsychiatric Inventory - Clinician Rating Scale (NPI-C). The clinical approach to and diagnosis of neuropsychiatric syndromes in dementia require suitable accuracy. Advances in the recognition and early accurate diagnosis of psychopathological symptoms help guide appropriate pharmacological and non-pharmacological interventions. In addition, recommended standardized and validated measurements contribute to both scientific research and clinical practice. Emotional distress, caregiver burden, and cognitive impairment often experienced by elderly caregivers, may affect the quality of caregiver reports. The clinician rating approach helps attenuate these misinterpretations. In this scenario, the NPI-C is a promising and versatile tool for assessing neuropsychiatric syndromes in dementia, offering good accuracy and high reliability, mainly based on the diagnostic impression of the clinician. This tool can provide both strategies: a comprehensive assessment of neuropsychiatric symptoms in dementia or the investigation of specific psychopathological syndromes such as agitation, depression, anxiety, apathy, sleep disorders, and aberrant motor disorders, among others.

Determination of lateral diffusion coefficients in air-water monolayers by fluorescence quenching measurements

1991 ◽  
Vol 113 (13) ◽  
pp. 4838-4843 ◽  
Author(s):  
F. Caruso ◽  
F. Grieser ◽  
A. Murphy ◽  
P. Thistlethwaite ◽  
R. Urquhart ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Diffusion Coefficients ◽  
Lateral Diffusion
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