Quantitative Estimation of Cyclotide-Induced Bilayer Membrane Disruption by Lipid Extraction with Mesoscopic Simulation

2021 ◽  
Author(s):  
Karina van den Broek ◽  
Matthias Epple ◽  
Lisa Sophie Kersten ◽  
Hubert Kuhn ◽  
Achim Zielesny
Keyword(s):  
Quantitative Estimation ◽  
Lipid Extraction ◽  
Bilayer Membrane ◽  
Membrane Disruption ◽  
Mesoscopic Simulation

scholarly journals Quantitative Estimation of Cyclotide-Induced Bilayer Membrane Disruption by Lipid Extraction with Mesoscopic Simulation

2021 ◽  
Author(s):  
Karina van den Broek ◽  
Matthias Epple ◽  
Lisa Sophie Kersten ◽  
Hubert Kuhn ◽  
Achim Zielesny
Keyword(s):  
Quantitative Estimation ◽  
Activity Patterns ◽  
Lipid Extraction ◽  
Dissipative Particle Dynamics ◽  
Interaction Model ◽  
Membrane Lipid ◽  
Membrane Disruption ◽  
Kinetic Rate Constant ◽  
Mesoscopic Simulation ◽  
Kalata B1

Cyclotide-induced membrane disruption is studied at the microsecond timescale by Dissipative Particle Dynamics (DPD) to quantitatively estimate a kinetic rate constant for membrane lipid extraction with a “sandwich” interaction model where two bilayer membranes enclose a cyclotide/water compartment. The obtained bioactivity trends for cyclotides Kalata B1, Cycloviolacin O2 and selected mutants with different membrane types are in agreement with experimental findings: For all membranes investigated, Cycloviolacin O2 shows a higher lipid extraction activity than Kalata B1. The presence of cholesterol leads to a decreased cyclotide activity compared to cholesterol-free membranes. Phosphoethanolamine-rich membranes exhibit an increased membrane disruption. A cyclotide’s “hydrophobic patch” surface area is important for its bioactivity. A replacement of or with charged amino acid residues may lead to super-mutants with above-native activity but without simple charge-activity patterns. Cyclotide mixtures show linearly additive bioactivities without significant sub- or over-additive effects.<br>

scholarly journals Quantitative Estimation of Cyclotide-Induced Bilayer Membrane Disruption by Lipid Extraction with Mesoscopic Simulation

2021 ◽  
Author(s):  
Karina van den Broek ◽  
Matthias Epple ◽  
Lisa Sophie Kersten ◽  
Hubert Kuhn ◽  
Achim Zielesny
Keyword(s):  
Quantitative Estimation ◽  
Activity Patterns ◽  
Lipid Extraction ◽  
Dissipative Particle Dynamics ◽  
Interaction Model ◽  
Membrane Lipid ◽  
Membrane Disruption ◽  
Kinetic Rate Constant ◽  
Mesoscopic Simulation ◽  
Kalata B1

Cyclotide-induced membrane disruption is studied at the microsecond timescale by Dissipative Particle Dynamics (DPD) to quantitatively estimate a kinetic rate constant for membrane lipid extraction with a “sandwich” interaction model where two bilayer membranes enclose a cyclotide/water compartment. The obtained bioactivity trends for cyclotides Kalata B1, Cycloviolacin O2 and selected mutants with different membrane types are in agreement with experimental findings: For all membranes investigated, Cycloviolacin O2 shows a higher lipid extraction activity than Kalata B1. The presence of cholesterol leads to a decreased cyclotide activity compared to cholesterol-free membranes. Phosphoethanolamine-rich membranes exhibit an increased membrane disruption. A cyclotide’s “hydrophobic patch” surface area is important for its bioactivity. A replacement of or with charged amino acid residues may lead to super-mutants with above-native activity but without simple charge-activity patterns. Cyclotide mixtures show linearly additive bioactivities without significant sub- or over-additive effects.<br>

A Resorcinol-Formaldehyde Resin as an Embedding Material for Electron Microscopy of Membranes

1969 ◽  
Vol 27 ◽  
pp. 328-329 ◽  
Author(s):  
J. G. Robertson ◽  
D. F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Osmium Tetroxide ◽  
Neutral Lipids ◽  
Lipid Extraction ◽  
Water Soluble ◽  
Formaldehyde Resin ◽  
Electron Microscope Autoradiography ◽  
Resorcinol Formaldehyde ◽  
Major Disadvantage ◽  
Cell Organization

The extraction of lipids from tissues during fixation and embedding for electron microscopy is widely recognized as a source of possible artifact, especially at the membrane level of cell organization. Lipid extraction is also a major disadvantage in electron microscope autoradiography of radioactive lipids, as in studies of the uptake of radioactive fatty acids by intestinal slices. Retention of lipids by fixation with osmium tetroxide is generally limited to glycolipids, phospholipids and highly unsaturated neutral lipids. Saturated neutral lipids and sterols tend to be easily extracted by organic dehydrating reagents prior to embedding. Retention of the more saturated lipids in embedded tissue might be achieved by developing new cross-linking reagents, by the use of highly water soluble embedding materials or by working at very low temperatures.

Plasma Fibrin Stabilising Factor (F. S. F.) Activity in Normal Subjects and Patients with Chronic Liver Disease

1969 ◽  
Vol 21 (01) ◽  
pp. 134-143 ◽  
Author(s):  
W. D Walls ◽  
M. S Losowsky
Keyword(s):  
Liver Disease ◽  
Chronic Liver Disease ◽  
Clinical Improvement ◽  
Quantitative Estimation ◽  
Kinetic Method ◽  
Normal Subjects ◽  
Chronic Liver ◽  
Clinical Severity ◽  
Plasma Fibrinogen ◽  
Normal Range

SummaryA kinetic method for the quantitative estimation of plasma F.S.F. activity is described and discussed.This method was applied to normal subjects and to patients with chronic liver disease. The plasma F.S.F. activity was uninfluenced by either sex or age, and the normal range has been defined.A significant decrease in plasma F.S.F. activity was observed in patients with chronic liver disease. Subnormal levels of activity were found in 25% of such patients but were unrelated to episodes of abnormal haemorrhage. Plasma F.S.F. activity tended to be lower in patients with disease of greater clinical severity. In 2 patients showing clinical improvement there was an increase in plasma F. S. F. activity.It was confirmed that plasma fibrinogen levels increase with age.

Social development of modern Russia: trends, risks, prospects

2018 ◽  
pp. 76-89
Author(s):  
E. M. Avraamova ◽  
V. N. Titov
Keyword(s):  
Middle Class ◽  
Social Development ◽  
Social Structure ◽  
Structure Formation ◽  
Resource Availability ◽  
Social Dynamics ◽  
Quantitative Estimation ◽  
Resource Potential ◽  
Institutional Conditions ◽  
Resource Characteristics

The analysis of present-time directions in the study of social development has allowed to identify the resource approach as the most productive one which enables to assess social dynamics through the range of resource characteristics of different population groups and abilities of the relevant groups to apply development resources in the current economic and institutional conditions. Basing on the sociological survey conducted by ISAP RANEPA, the quantitative estimation of material and social recourses of the population has been made; integral values of the resource potential have been calculated as well. The issues of social structure formation are analyzed through the aspect of resource availability; the barriers of Russian middle-class enlargement are defined.

QUANTITATIVE ESTIMATION OF URINARY PREGNANETRIOL, PREGNANETRIOLONE, TETRAHYDRO S AND Δ5-PREGNENETRIOL IN THE INVESTIGATION OF ADRENOCORTICAL FUNCTION

1969 ◽  
Vol 60 (4) ◽  
pp. 657-668 ◽  
Author(s):  
Frances J. Thomas ◽  
A. W. Steinbeck
Keyword(s):  
Congenital Adrenal Hyperplasia ◽  
Cushing’S Syndrome ◽  
Adrenocortical Carcinoma ◽  
Quantitative Estimation ◽  
Cushing's Syndrome ◽  
Adrenocortical Function ◽  
Adrenal Hyperplasia ◽  
Ectopic Acth ◽  
Modified Method ◽  
Idiopathic Hirsutism

ABSTRACT A modified method for the estimation of urinary pregnanetriol, pregnanetriol, pregnanetriolone, Δ5-pregnenetriol and tetrahydro S was investigated. The steroids, separated by chromatography, were measured quantitatively, tetrahydro S by reaction with blue tetrazolium and the other three as acetaldehydogenic substances. The excretion of these steroids was studied in suspected instances of adrenal and/or ovarian disease. Urinary pregnanetriol and tetrahydro S levels were normal in Cushing's syndrome, secondary adrenocortical carcinoma, the Stein-Leventhal syndrome, idiopathic hirsutism and hypertension. Tetrahydro S was doubtfully elevated in an instance of ectopic ACTH Cushing's syndrome. Pregnanetriol excretion was elevated in untreated cases of congenital adrenal hyperplasia and after treatment in some. Pregnanetriolone was found in all patients with congenital adrenal hyperplasia, including those receiving cortisone. Pregnanetriolone was also detected in Cushing's syndrome, secondary adrenocortical carcinoma, the Stein-Leventhal syndrome, ectopic ACTH Cushing's syndrome and suspected congenital adrenal hyperplasia. Δ5-pregnenetriol was present as a glucuronide in the Stein-Leventhal syndrome and idiopathic hirsutism. The diagnostic implications of these results are discussed.

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