osmotic pressure
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2022 ◽  
Author(s):  
Qi Zhou ◽  
Ping Wang ◽  
Bei-Bei Ma ◽  
Zhong-Ying Jiang ◽  
Tao Zhu

Abstract Osmotic pressure can break the fluid balance between intracellular and extracellular solutions. In hypo-osmotic solution, water molecules, which transfer into the cell and burst, are driven by the concentrations difference of solute across the semi-permeable membrane. The complicated dynamic processes of the intermittent burst have been previously observed. However, the underlying physical mechanism has yet to be thoroughly explored and analyzed. Here, the intermittent release of inclusion in giant unilamellar vesicles was investigated quantitatively, applying the combination of experimental and theoretical methods in the hypo-osmotic medium. Experimentally, we adopted highly sensitive EMCCD to acquire intermittent dynamic images. Notably, the component of the vesicle phospholipids affected the stretch velocity, and the prepared solution of the vesicle adjusted the release time. Theoretically, we chose equations numerical simulations to quantify the dynamic process in phases and explored the influence of physical parameters such as bilayer permeability and solution viscosity on the process. It was concluded that the time taken to achieve the balance of giant unilamellar vesicles was highly dependent on the structure of the lipid molecular. The pore lifetime was strongly related with the internal solution environment of giant unilamellar vesicles. The vesicle prepared in viscous solution accessed visualized long-lived pore. Furthermore, the line tension was measured quantitatively by the release velocity of inclusion, which was in the same order of magnitude as the theoretical simulation. In all, the experimental values well matched the theoretical values. Our investigation clarified the physical regulatory mechanism of intermittent pore formation and inclusion release, which had an important reference for the development of novel technologies such as gene therapy based on transmembrane transport as well as controlled drug delivery based on liposomes.


2022 ◽  
Vol 933 ◽  
Author(s):  
Rouae Ben Dhia ◽  
Nils Tilton ◽  
Denis Martinand

We use linear stability analysis and direct numerical simulations to investigate the coupling between centrifugal instabilities, solute transport and osmotic pressure in a Taylor–Couette configuration that models rotating dynamic filtration devices. The geometry consists of a Taylor–Couette cell with a superimposed radial throughflow of solvent across two semi-permeable cylinders. Both cylinders totally reject the solute, inducing the build-up of a concentration boundary layer. The solute retroacts on the velocity field via the osmotic pressure associated with the concentration differences across the semi-permeable cylinders. Our results show that the presence of osmotic pressure strongly alters the dynamics of the centrifugal instabilities and substantially reduces the critical conditions above which Taylor vortices are observed. It is also found that this enhancement of the hydrodynamic instabilities eventually plateaus as the osmotic pressure is further increased. We propose a mechanism to explain how osmosis and instabilities cooperate and develop an analytical criterion to bound the parameter range for which osmosis fosters the hydrodynamic instabilities.


Author(s):  
Fulin Dong ◽  
Song Liu ◽  
Duohuai Zhang ◽  
Jinchang Zhang ◽  
Xiaoling Wang ◽  
...  

2021 ◽  
Vol 8 ◽  
Author(s):  
Bo Lv ◽  
Linhui Hu ◽  
Heng Fang ◽  
Dayong Sun ◽  
Yating Hou ◽  
...  

Backgrounds: The plasma colloid osmotic pressure (COP) values for predicting mortality are not well-estimated. A user-friendly nomogram could predict mortality by incorporating clinical factors and scoring systems to facilitate physicians modify decision-making when caring for patients with serious neurological conditions.Methods: Patients were prospectively recruited from March 2017 to September 2018 from a tertiary hospital to establish the development cohort for the internal test of the nomogram, while patients recruited from October 2018 to June 2019 from another tertiary hospital prospectively constituted the validation cohort for the external validation of the nomogram. A multivariate logistic regression analysis was performed in the development cohort using a backward stepwise method to determine the best-fit model for the nomogram. The nomogram was subsequently validated in an independent external validation cohort for discrimination and calibration. A decision-curve analysis was also performed to evaluate the net benefit of the insertion decision using the nomogram.Results: A total of 280 patients were enrolled in the development cohort, of whom 42 (15.0%) died, whereas 237 patients were enrolled in the validation cohort, of which 43 (18.1%) died. COP, neurological pathogenesis and Acute Physiology and Chronic Health Evaluation II (APACHE II) score were predictors in the prediction nomogram. The derived cohort demonstrated good discriminative ability, and the area under the receiver operating characteristic curve (AUC) was 0.895 [95% confidence interval (CI), 0.840–0.951], showing good correction ability. The application of this nomogram to the validation cohort also provided good discrimination, with an AUC of 0.934 (95% CI, 0.892–0.976) and good calibration. The decision-curve analysis of this nomogram showed a better net benefit.Conclusions : A prediction nomogram incorporating COP, neurological pathogenesis and APACHE II score could be convenient in predicting mortality for critically ill neurological patients.


2021 ◽  
Vol 36 (1) ◽  
Author(s):  
Yosuke Ida ◽  
Araya Umetsu ◽  
Masato Furuhashi ◽  
Megumi Watanabe ◽  
Fumihito Hikage ◽  
...  

2021 ◽  
Author(s):  
Joёl Lemière ◽  
Paula Real-Calderon ◽  
Liam J. Holt ◽  
Thomas G. Fai ◽  
Fred Chang

AbstractThe size of the nucleus scales robustly with cell size so that the nuclear-to-cell volume ratio (N/C ratio) is maintained during cell growth in many cell types. The mechanism responsible for this scaling remains mysterious. Previous studies have established that the N/C ratio is not determined by DNA amount, but is instead influenced by factors such as nuclear envelope mechanics and nuclear transport. Here, we developed a quantitative model for nuclear size control based upon colloid osmotic pressure and tested key predictions in the fission yeast Schizosaccharomyces pombe. This model posits that the N/C ratio is determined by the numbers of macromolecules in the nucleoplasm and cytoplasm. Osmotic shift experiments showed that the fission yeast nucleus behaves as an ideal osmometer whose volume is primarily dictated by osmotic forces. Inhibition of nuclear export caused accumulation of macromolecules and an increase in crowding in the nucleoplasm, leading to nuclear swelling. We further demonstrated that the N/C ratio is maintained by a homeostasis mechanism based upon synthesis of macromolecules during growth. These studies demonstrate the functions of colloid osmotic pressure in intracellular organization and size control.


2021 ◽  
pp. 110886
Author(s):  
Yifang Cao ◽  
Li Li ◽  
Yan Zhang ◽  
Fengsong Liu ◽  
Xinglong Xiao ◽  
...  

Author(s):  
Radhika Mishra ◽  
Ariunbuyan Sukhbaatar ◽  
Sora Shouta ◽  
Maya Sakamoto ◽  
Shiro Mori ◽  
...  

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