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Advances in Physiology Education Jun 2022This study proposes a hands-on activity as an experimental alternative method to teach biomedical engineering students the osmosis phenomenon. The students were guided...
This study proposes a hands-on activity as an experimental alternative method to teach biomedical engineering students the osmosis phenomenon. The students were guided along a learning path that involved their participation in the design and construction of a test device used to measure osmotic flow rate. Thereafter, an experiment was conducted with the test device. The students analyzed the obtained experimental values, which provided them with evidence of the functionality of the device. In addition, they were provided with the opportunity to suggest improvements and to propose alternatives to expand the use of the device to test other transport phenomena such as diffusion. Moreover, a student perception survey was conducted, and the results showed that this proposed plan allows for a better understanding of the phenomenon and stimulates the curiosity of students, improving the receptiveness, key in the learning process of the students.
Topics: Biomedical Engineering; Humans; Learning; Osmosis; Students; Teaching
PubMed: 35085036
DOI: 10.1152/advan.00186.2020 -
Proceedings of the National Academy of... Nov 2021During osmotic changes of their environment, cells actively regulate their volume and plasma membrane tension that can passively change through osmosis. How tension and...
During osmotic changes of their environment, cells actively regulate their volume and plasma membrane tension that can passively change through osmosis. How tension and volume are coupled during osmotic adaptation remains unknown, as their quantitative characterization is lacking. Here, we performed dynamic membrane tension and cell volume measurements during osmotic shocks. During the first few seconds following the shock, cell volume varied to equilibrate osmotic pressures inside and outside the cell, and membrane tension dynamically followed these changes. A theoretical model based on the passive, reversible unfolding of the membrane as it detaches from the actin cortex during volume increase quantitatively describes our data. After the initial response, tension and volume recovered from hypoosmotic shocks but not from hyperosmotic shocks. Using a fluorescent membrane tension probe (fluorescent lipid tension reporter [Flipper-TR]), we investigated the coupling between tension and volume during these asymmetric recoveries. Caveolae depletion and pharmacological inhibition of ion transporters and channels, mTORCs, and the cytoskeleton all affected tension and volume responses. Treatments targeting mTORC2 and specific downstream effectors caused identical changes to both tension and volume responses, their coupling remaining the same. This supports that the coupling of tension and volume responses to osmotic shocks is primarily regulated by mTORC2.
Topics: Actins; Cell Membrane; Cell Size; Cytoskeleton; HeLa Cells; Humans; Membranes; Models, Theoretical; Osmosis; Osmotic Pressure
PubMed: 34785592
DOI: 10.1073/pnas.2103228118 -
Kidney International Feb 1982
Topics: Hydrostatic Pressure; Kinetics; Membranes; Osmosis; Osmotic Pressure; Temperature
PubMed: 7069994
DOI: 10.1038/ki.1982.22 -
Anesthesiology Nov 2010
Topics: Animals; Brain Injuries; Cell Membrane Permeability; Edema; Fluid Therapy; Osmosis; Rats
PubMed: 20966675
DOI: 10.1097/ALN.0b013e3181f70f6d -
Proceedings of the National Academy of... Mar 1994Most reactions involved in gene translation systems are ionic-dependent and may be explained in electrostatic terms. However, a number of observations of equilibria and... (Review)
Review
Most reactions involved in gene translation systems are ionic-dependent and may be explained in electrostatic terms. However, a number of observations of equilibria and rate processes making up the overall reactions clearly indicate that there is still an enormous gap between the rough picture of the mechanism of ionic regulation and the detailed behavior of reactions at the molecular level that hold the key to specific mechanisms. The present paper deals with possible osmotic contributions arising from the gel state of gene systems that are complementary to, and interdependent of, electrostatic contributions. This treatment, although still oversimplified, explains many previous observations by relating them to a general osmotic mechanism and suggests experimental approaches to studying the mechanisms of gene regulation in organelle-free and intact systems.
Topics: Biopolymers; Cations; Escherichia coli; Gels; Gene Expression Regulation; Gene Expression Regulation, Bacterial; Models, Biological; Osmosis; Ribosomes
PubMed: 8127862
DOI: 10.1073/pnas.91.5.1657 -
Seminars in Cell & Developmental Biology Jun 2008Two views have dominated recent discussions of the physical basis of cell shape change during migration and division of animal cells: the cytoplasm can be modeled as a... (Review)
Review
Two views have dominated recent discussions of the physical basis of cell shape change during migration and division of animal cells: the cytoplasm can be modeled as a viscoelastic continuum, and the forces that change its shape are generated only by actin polymerization and actomyosin contractility in the cell cortex. Here, we question both views: we suggest that the cytoplasm is better described as poroelastic, and that hydrodynamic forces may be generally important for its shape dynamics. In the poroelastic view, the cytoplasm consists of a porous, elastic solid (cytoskeleton, organelles, ribosomes) penetrated by an interstitial fluid (cytosol) that moves through the pores in response to pressure gradients. If the pore size is small (30-60nm), as has been observed in some cells, pressure does not globally equilibrate on time and length scales relevant to cell motility. Pressure differences across the plasma membrane drive blebbing, and potentially other type of protrusive motility. In the poroelastic view, these pressures can be higher in one part of a cell than another, and can thus cause local shape change. Local pressure transients could be generated by actomyosin contractility, or by local activation of osmogenic ion transporters in the plasma membrane. We propose that local activation of Na(+)/H(+) antiporters (NHE1) at the front of migrating cells promotes local swelling there to help drive protrusive motility, acting in combination with actin polymerization. Local shrinking at the equator of dividing cells may similarly help drive invagination during cytokinesis, acting in combination with actomyosin contractility. Testing these hypotheses is not easy, as water is a difficult analyte to track, and will require a joint effort of the cytoskeleton and ion physiology communities.
Topics: Animals; Cell Movement; Cell Shape; Cytoplasm; Elasticity; Osmosis; Viscosity
PubMed: 18395478
DOI: 10.1016/j.semcdb.2008.01.008 -
Cancer Science Aug 2019Cancer metastasis is the most frequent cause of death for patients with cancer. The main current treatment for cancer metastasis is chemotherapy targeting cancer cells'... (Review)
Review
Cancer metastasis is the most frequent cause of death for patients with cancer. The main current treatment for cancer metastasis is chemotherapy targeting cancer cells' ability to proliferate. However, some types of cancer cells show resistance to chemotherapy. Recently, cancer cell migration has become the subject of interest as a novel target of cancer therapy. Cell migration requires many factors, such as the cytoskeleton, cell-matrix adhesion and cell volume regulation. Here, we focus on cell volume regulation and the role of ion/water transport systems in cell migration. Transport proteins, such as ion channels, ion carriers, and aquaporins, are indispensable for cell volume regulation under steady-state conditions and during exposure to osmotic stress. Studies from the last ~25 years have revealed that cell volume regulation also plays an important role in the process of cell migration. Water flow in accordance with localized osmotic gradients generated by ion transport contributes to the driving force for cell migration. Moreover, it has been reported that metastatic cancer cells have higher expression of these transport proteins than nonmetastatic cancer cells. Thus, ion/water transport proteins involved in cell volume regulation and cell migration could be novel therapeutic targets for cancer metastasis. In this review, after presenting the importance of ion/water transport systems in cell volume regulation, we discuss the roles of transport proteins in a pathophysiological context, especially in the context of cancer cell migration.
Topics: Animals; Cell Movement; Cell Size; Humans; Ion Transport; Membrane Transport Proteins; Neoplasms; Osmosis; Protein Transport; Water
PubMed: 31120184
DOI: 10.1111/cas.14079 -
Physiological Reports Jan 2020Most of the filtered glucose is reabsorbed in the early proximal tubule by the sodium-glucose cotransporter SGLT2. The glycosuric effect of the SGLT2 inhibitor...
Most of the filtered glucose is reabsorbed in the early proximal tubule by the sodium-glucose cotransporter SGLT2. The glycosuric effect of the SGLT2 inhibitor ipragliflozin is linked to a diuretic and natriuretic effect that activates compensatory increases in fluid and food intake to stabilize body fluid volume (BFV). However, the compensatory mechanisms that are activated on the level of renal tubules remain unclear. Type 2 diabetic Goto-Kakizaki (GK) rats were treated with vehicle or 0.01% (in diet) ipragliflozin with free access to fluid and food. After 8 weeks, GK rats were placed in metabolic cages for 24-hr. Ipragliflozin decreased body weight, serum glucose and systolic blood pressure, and increased fluid and food intake, urinary glucose and Na excretion, urine volume, and renal osmolar clearance, as well as urine vasopressin and solute-free water reabsorption (TcH2O). BFV, measured by bioimpedance spectroscopy, and fluid balance were similar among the two groups. Urine vasopressin in ipragliflozin-treated rats was negatively and positively associated with fluid balance and TcH2O, respectively. Ipragliflozin increased the renal membrane protein expression of SGLT2, aquaporin (AQP) 2 phosphorylated at Ser269 and vasopressin V2 receptor. The expression of SGLT1, GLUT2, AQP1, and AQP2 was similar between the groups. In conclusion, the SGLT2 inhibitor ipragliflozin induced a sustained glucosuria, diuresis, and natriuresis, with compensatory increases in fluid intake and vasopressin-induced TcH2O in proportion to the reduced fluid balance to maintain BFV. These results indicate that the osmotic diuresis induced by SGLT2 inhibition stimulates compensatory fluid intake and renal water reabsorption to maintain BFV.
Topics: Animals; Body Fluid Compartments; Body Fluids; Diuresis; Diuretics, Osmotic; Glucosides; Osmosis; Rats; Renal Reabsorption; Sodium-Glucose Transporter 2 Inhibitors; Thiophenes; Vasopressins; Water
PubMed: 31994353
DOI: 10.14814/phy2.14360 -
Sensors (Basel, Switzerland) Dec 2022Design and implementation of an open-source-based supervisory control and data acquisition (SCADA) system for a community solar-powered reverse osmosis are presented in...
Design and implementation of an open-source-based supervisory control and data acquisition (SCADA) system for a community solar-powered reverse osmosis are presented in this paper. A typical SCADA system available on the market is proprietary and has a high initial and maintenance cost. Aside from that, there is no SCADA system with an alert system available to give users updates and status information concerning the system. The objective of this study is to develop a comprehensive SCADA design that takes advantage of open-source technology to address the world's most pressing problem, access to clean water. The designed reverse Osmosis system also uses renewable energy-based power sources. In this system, all data is stored and analyzed locally, which ensures the data is secure and allows the user to make data-driven decisions based on the collected data. Among the main components of this system are the field instrument devices (FIDs), the remote terminal unit (RTU), the main terminal units (MTUs), the web-based programming software, and the data analytics software. The Node-Red programming and dashboard tool, Grafana for data analytics, and InfluxDB for database management run on the main terminal unit having Debian operating system. Data is transmitted from the FIDs to the RTU, which then redirects it to the MTU via serial communication. Node-Red displays the data processed by the MTU on its dashboard as well, as the data is stored locally on the MTU and is displayed by means of Grafana, which is also installed on the same MTU. Through the Node-Red dashboard, the system is controlled, and notifications are sent to the community.
Topics: Software; Water; Technology; Solar Energy; Osmosis
PubMed: 36559999
DOI: 10.3390/s22249631 -
Kidney International. Supplement Apr 2008The achievement of euvolemia is essential to the successful management of peritoneal dialysis patients. However, the concern that hypertonic glucose exchanges may have a... (Review)
Review
The achievement of euvolemia is essential to the successful management of peritoneal dialysis patients. However, the concern that hypertonic glucose exchanges may have a role in long-term changes to the peritoneal membrane has lead to an alternative strategy to enhance ultrafiltration (UF) over the long dwell by combining crystalloid and colloid osmosis. This review summarizes the experience of mixing glucose or amino acids with polyglucose (icodextrin), with particular focus given to data from studies using glucose/icodextrin in combinations of 1.36%/7.5% and 2.61%/6.8%. Both combinations demonstrate a significant increment of UF volume and sodium removal compared with the component osmotic agents used individually over long dwells, with the 2.61%/6.8% mixture having an effect over dwells extending to 15 h. Hypothetically, the mechanism of the enhanced UF is the attenuation by the colloid osmotic force of the backflow of water through small pores from dialysate to the peritoneal capillary circulation once the crystalloid osmotic force has dissipated. This experience provides promising data that deserves further examination in longer term clinical studies.
Topics: Colloids; Crystalloid Solutions; Dialysis Solutions; Glucans; Glucose; Humans; Icodextrin; Isotonic Solutions; Osmosis; Peritoneal Dialysis, Continuous Ambulatory; Sodium; Water-Electrolyte Balance
PubMed: 18379532
DOI: 10.1038/sj.ki.5002610