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A Biophysical View on the Function and Activity of Endotoxins
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Ulrich Seydel, Andre Wiese, Andra B. Schromm, Klaus Brandenburg
Membranes, in general, constitute the boundary between a cell or a cell compartment and its environment. They are composed of (glyco)lipids and proteins, function as permeability barriers, maintain constant ion gradients across the membrane, and guarantee a controlled steady state of fluxes in the cell. Furthermore, the vast majority of cell membranes carry recognition sites for components of the immune system and for interaction/communication with other cells.
Physiology of Excitable Cells
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The presence of a membrane potential allows electrical communication between cells. For example, a motor nerve, when activated in the spinal cord, relays this information along the axon and releases transmitters by a progressive and propagated reversal of membrane potential. Skeletal muscle contraction is produced by a propagated change in membrane potential spreading over the cell, precipitating the release of calcium from intracellular stores. Afferent nerves are activated by special sense organs and transmit this information by electrical axonal activation and release of neurotransmitters, altering the membrane potential and function of central nervous system cells. In the heart, regular changes in the muscle cell ionic permeability and potential produce cardiac autorhythmicity. In all these examples, alterations in the membrane potential lead to communication between cells.
In Vitro Techniques to Study the Transport of Radiotracers
Published in Lelio G. Colombetti, Biological Transport of Radiotracers, 2020
Marco Salvatore, Luigi Mansi, Gianni Morrone, Rosa Ferraiuolo, Salvatore Venuta
Isolated biological membranes have an important role in the study of the mechanism of transport. The use of this system allows the identification of the function the plasma membrane performs in regulating the accumulation of radiotracers.17 Many studies were already made with cell cultures18-21 using different systems.
Protein transduction domain of translationally controlled tumor protein: characterization and application in drug delivery
Published in Drug Delivery, 2022
Biological membranes consist of lipid bilayers in which proteins are embedded. These membranes separate the cytoplasm from the extracellular milieu by regulating the movement of molecules across the membrane. These selectively permeable barriers limit the internalization of external molecules such as specific medications and drugs, unless specific mechanisms such as endocytosis are involved (Joliot & Prochiantz, 2004). As the target molecules for specific medications need to enter the interior of the cells to be effective, there has been great research interest in vehicles that enable the efficient intracellular delivery of therapeutic macromolecules. The discovery of peptide moieties that can translocate into the cells opens up new ways to deliver various types of potential medicinal cargoes, such as small and large molecules including chemicals, peptides, proteins, antisense nucleotides, and liposomes. These peptide moieties are generally called protein transduction domains (PTDs) or cell-penetrating peptides (CPPs).
Glucosamine modulates membrane and cellular ionic homeostasis: studies on accelerated senescent and naturally aged rats
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Komal Saraswat, Raushan Kumar, Syed Ibrahim Rizvi
It has been suggested that biochemical and biophysical abnormalities of cell membranes may actively participate in the pathogenesis of age-related diseases [27]. Membrane-bound calcium-transporting protein PMCA pump is important in regulating various signaling functions of calcium [31]. Erythrocytes have deformability and elasticity properties which are affected by Ca2+ ions [32]. Elevation in internal Ca2+ levels leads to changes in cell shape and volume, increased cellular rigidity, and hemolysis [33]. Since this pump plays a crucial role in the maintenance of internal Ca2+ levels by creating a concentration gradient between cytosol and extracellular fluid, it can be predicted that aging results in alteration of PMCA pump activity [34]. Altered activity of erythrocyte PMCA has been reported in aging [35] which can be seen in our results too. However, upregulation of PMCA activity by glucosamine supplementation signifies its possible shielding effect against cellular redox imbalance in aging and associated diseases.
There and back again: a dendrimer’s tale
Published in Drug and Chemical Toxicology, 2022
Barbara Ziemba, Maciej Borowiec, Ida Franiak-Pietryga
If we consider dendrimers as tools in nanomedicine, their ability to cross the cell membrane is a crucial requirement. The cell membrane has two function. Firstly, it is a barrier keeping the constituents of the cell inside and unwanted substances outside, and secondly it is a gate that enables the transport of essential nutrients into the cell and the movement of metabolic products from the cell. The lipid bilayer which is largely made up of phospholipids and cholesterol, strewn with proteins and other biomolecules, results in an overall negative charge of the plasma membrane. It is also characterized by several cationic domains and selective permeability to ions, molecules, and nanoparticles (Cooper 2000). The crucial issue is to know how nanoparticles (including dendrimers) enter cells as the underlying uptake pathways determine the nanoparticle’s function, intracellular fate, and biological response (Donahue et al.2019).