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Body fluids and electrolytes
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
The intracellular and extracellular compartments are separated by the cell plasma membranes, whereas the interstitial and transcellular compartments are separated by the cell membranes of the particular tissues involved. The blood vessel wall separates the blood from the interstitial fluid. It is only at the arteriolar and capillary levels that there is interaction between these two parts of the extracellular compartment. The capillary walls have a selectively permeable membrane, permeable to most molecules in the plasma except for plasma proteins and red blood cells, which are too large to move through the capillary wall. This selective permeability helps to maintain the unique composition of each compartment, while allowing for movement of nutrients and oxygen from the plasma to the cells, and movement of waste products out of the cells and into the plasma.
Herbal Product Development and Characteristics
Published in Anil K. Sharma, Raj K. Keservani, Surya Prakash Gautam, Herbal Product Development, 2020
Mirian Pateiro, Rubén Domínguez, Predrag Putnik, Danijela Bursać Kovačević, Francisco J. Barba, Paulo S. E. Munekata, Elena Movilla Fierro, José M. Lorenzo
The biomembranes are cellular structures that surround living organisms. They are formed by a double lipid layer, which confers with one of its most important functions, as regulation of the entry and exit of macromolecules, whether or not this is intracellular or extracellular delivery. In addition, they are also characterized by possessing capacity for selective permeability. Biomembranes also contain three types of proteins, such as ion channels, receptors, and transporters which allow the exchange of substances with other cells or tissues. The presence of polyphenols can modify activity of these proteins, what could change the interactions with phospholipids (Figure 8.3b) (Wink, 2015).
Membrane Properties of Peritoneal Macrophage
Published in Richard C. Niemtzow, Transmembrane Potentials and Characteristics of Immune and Tumor Cell, 2020
Most cell membranes develop potentials through a mechanism of selective permeability. A more thorough discussion of membrane selectivity is given in Chapter 1. However, in most cells, the permeability to K+ is usually high, while permeabilities to Na+ and Cl- are low. These ion gradients are usually maintained by a Na+-K+ transport system driven by ATP cleavage. The result of the selective permeability to K+ is generally a membrane potential that has the inside negative with respect to the outside. One manner of assessing the permeability to various ions is to vary the external ionic environment and note any changes in membrane potential. The relative permeabilities can then be calculated from the equation17, 26
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).
The potential protective roles of zinc, selenium and glutathione on hypoxia-induced TRPM2 channel activation in transfected HEK293 cells
Published in Journal of Receptors and Signal Transduction, 2020
Dilek Duzgun Ergun, Sefik Dursun, Nural Pastaci Ozsobaci, Ozden Hatırnaz Ng, Mustafa Naziroglu, Dervis Ozcelik
It was showed that under hypoxic conditions nicotinamide adenine dinucleotide phosphate (NADPH), an oxidative stress enzyme, expression and ROS increase in mesenchymal stromal cells isolated from Sprague-Dawley rat femurs, and as a result, cell viability is decreased due to increased LDH activity [26]. Results of our study showed LPO levels and LDH% values increased in parallel with the increase of free oxygen radicals in HEK293 cells are exposed to hypoxia. When oxidant/antioxidant balance is disturbed after the hypoxia, release of pro-apoptotic proteins, which cause apoptosis increases as a result of the damage to the biomolecules such as proteins, lipids, carbohydrates and nucleic acids. This, in return, damages the integrity and selective permeability of cell membrane, and trigger cellular damage [27–29]. Increased LDH% values in the hypoxic groups compared to the normoxic groups in our study demonstrates that hypoxia increased cellular damage and cytotoxicity, and therefore cell death. The findings of our study are in line with the literature information on oxidative effects of hypoxia. More importantly, however, this study showed that duration of the hypoxia application affects the increase in LPO levels, and LDH% values.
Vision of bacterial ghosts as drug carriers mandates accepting the effect of cell membrane on drug loading
Published in Drug Development and Industrial Pharmacy, 2020
Fars K. Alanazi, Abdulaziz A. Alsuwyeh, Nazrul Haq, Mounir M. Salem-Bekhit, Abdullah Al-Dhfyan, Faiyaz Shakeel
Gram negative envelope, cell wall, and inner plasma membrane, can affect both drug loading and release. Cell wall is composed of outer membrane, peptidoglycan layer, and periplasm [25]. The outer membrane is rich in lipid while the peptidoglycan layer is thin. Therefore, understanding the role of these components leads to better understanding of drug transport. Thus, the outer membrane has selective permeability since it is porous to certain substances. Periplasmic constituent works as border guard to maintain cells’ live-hood due to its gel like entrapping matrices. Moreover, cell wall can persist pressure up to 3 atm. It also gives bacteria the protection against extreme change in pH and temperature. Finally, the cell wall considers tough, elastic and plays important role in drug trafficking in or out the BGs. The amount of DOX loaded inside the BGs was determined in this study instead of its determination on the surface of BGs. Hence, this process can be considered as an encapsulation instead of adsorption of DOX on the surface of BGs. In addition, the current study is focusing on selected factors that could be controlled to ensure drug loading in the following section.