Physical technology and biological basis of hyperthermia in oncology
Clifford L. K. Pang, Kaiman Lee in Hyperthermia in Oncology, 2015
Heating can affect both cell nuclei and cytoplasm. It can act on cell nuclei directly, causing loss of cellular polymerase activity, and can also act indirectly on DNA synthesis, chromosomal and intracellular components, cytoskeletons, and so on, causing a series of reactions. A cell membrane has a phospholipid bilayer, and its viscosity varies with temperature. Any factor increasing the membrane fluidity will exacerbate the damage caused by high temperature. Membrane damage is likely to be one of the reasons for apoptosis. The killing energy of hyperthermia is consistent with that of protein damage and synthesis depression. The cell cannot continue its division after the damage of cell membrane, so it will die at phase G. The high temperature of 45°C can induce chromosomal aberrations and damage to DNA-related enzymes, resulting in cell death. Tumor cells are sensitive to heat. When they are heated to 43°C for 30 minutes, cell apoptosis occurs, and when they are heated to 46°C or more for 30 minutes, cell necrosis occurs. Figure 3.1 shows the differences between cell necrosis and apoptosis.
Metabolism of Phosphonates
Richard L. Hilderbrand in The Role of Phosphonates in Living Systems, 2018
A new strain of T. pyriformis, called NT-1, has been isolated which, unlike the most commonly used strain WH-14,94 shows temperature-dependent alteration of the phospholipid composition of the organism.95,96 On temperature shift from 39.5 to 15°C the phosphonolipid increases from 16 to 29% of the total phospholipids while phosphatidylethanolamine drops from 43 to 26%, the same pattern observed on AEP feeding. There is also an increase in the unsaturation of the fatty acids in response to the temperature decrease as a potential means of maintaining membrane fluidity.96 Whether the phospholipid base change is also a means of altering membrane fluidity or is merely a consequence of the different fatty acid and glyceryl ether contents of the various phospholipids remains to be determined.97
The Cell Membrane in the Steady State
Nassir H. Sabah in Neuromuscular Fundamentals, 2020
In living cells, the basic phospholipid bilayer structure is modified in several respects so as to serve the many important functions required of the cell membrane. Cell membranes have an abundance of cholesterol and protein molecules (Figure 2.2). Cholesterol is a small steroid-type molecule having a hydrophilic OH group, that aligns with the polar heads of the phospholipid molecules, and a hydrophobic portion that nestles between the fatty acid chains. On the one hand, cholesterol makes the membrane more fluid and flexible by preventing the fatty acid chains from forming a more rigid, crystal-like structure. On the other hand, the attraction to the fatty acid chains makes the membrane firmer and less permeable to small, water-soluble molecules. In addition, cholesterol plays a significant role in mechanically securing protein molecules in the membrane so that they are not adversely affected by membrane fluidity.
Tinospora Cordifolia and Arabinogalactan in combination modulates benzo(a)pyrene-induced genotoxicity during lung carcinogenesis
Published in Drug and Chemical Toxicology, 2022
Yongli Chang, Diancui Zhang, Junxia Cui, Anshoo Malhotra
The membrane fluidity is crucial for optimization of membrane dynamics of a cell. In other words, membrane fluidity is the freedom of the relative motion in the membrane lipid bilayer (Li et al.2021). These dynamic features allow rotational or lateral diffusion of molecules. BP treatment revealed an increase in E/M ratio in comparison to normal control group. On the other hand, observance of the increased E/M ratio of the probe [pyrene] signified decline in membrane microviscosity. This decline in membrane viscosity leads to rise in membrane fluidity. In other words, alterations in membrane dynamics favored cancer initiation (Kaur and Sanyal 2010, Oommen et al.2016, Bhardwaj et al.2019). The above observation could be owed to rise in lateral diffusion as noticed by recording of high degree of freedom of the probe in the hydrocarbon phase. On the other hand, administration of combination of Aq.Tc and AG to BP treated rats significantly decreased the E/M ratio leading to significant decline in membrane fluidity. The observed decrease in membrane fluidity in BP treated rats could be linked with the regulatory role of combination of Aq.Tc and AG. So, it is quite clear from these observations that combination of Aq.Tc and AG are capable of regulating membrane dynamics in lung cancers cell, thereby, preventing the invasion phase of carcinogenesis.
Rich fatty acids diet of fish and olive oils modifies membrane properties in striatal rat synaptosomes
Published in Nutritional Neuroscience, 2021
Adriana Morales-Martínez, Absalom Zamorano-Carrillo, Sergio Montes, Mohammed El-Hafidi, Alicia Sánchez-Mendoza, Elizabeth Soria-Castro, Juan Carlos Martínez-Lazcano, Pablo Eliasib Martínez-Gopar, Camilo Ríos, Francisca Pérez-Severiano
Cells are defined by barriers called membranes, which are selective and can communicate and separate cells and their internal organelles [1]. In particular, the plasmatic membrane consists of a lipid bilayer composed by phospholipids, amphipathic molecules that provide basic fluid structure [2]. Membrane fluidity is a measurement of molecular mobility inside the lipid bilayer that allows for lateral diffusion of proteins embedded; hence, biological membranes require high lateral fluidity and structural rigidity [3]. In the neuronal membrane, 50% of are fatty acids, where the fluidity is an important property that promotes optimal receptor function [4,5]. Further, fluidity can be modified by changing the profile of polyunsaturated fatty acids (PUFAs) of membrane phospholipids [4]. Long chain PUFAs, like eicosapentaenoic acid (EPA, 20:5 n-3), docosahexaenoic acid (DHA, 22:6 n-3), and arachidonic acid (AA, 20:4 n-6), are produced by elongation and unsaturation of essential fatty acids (EFAs) included in the diet [2]. PUFAs and their metabolites carry out physiological functions: energy supply, membrane structure, cellular signaling, and regulation of gene expression [6]. Several oils are rich in PUFAs and other fatty acids. In this regard, olive oil has a high ratio of oleic and linoleic acids [7], while fish oil contains DHA and EPA in high proportion [8].
Synthesis and therapeutic delivery approaches for praziquantel: a patent review (2010-present)
Published in Expert Opinion on Therapeutic Patents, 2021
Tayo A. Adekiya, Pradeep Kumar, Pierre P.D. Kondiah, Viness Pillay, Yahya E. Choonara
The polar heads at one surface of the membrane facing the aqueous interior layer of LBNSs and those at the other surface points at the aqueous exterior environment. This chemical tendency is the approach used to form liquid filled spheres, which allows the LBNSs to be loaded with drugs or other bioactive compounds. The formation of LBNSs leads to the incorporation of water-soluble molecules into the aqueous interior, while the lipophilic molecules will tend to be incorporated into the lipid-bilayer. These attributes make them to play a crucial role in maintaining the cell membrane fluidity. Conversely, the developments of amphiphilic drug-lipid complex or pharmacosomes improve drug potential and make it easier to penetrate cell membrane without altering the cellular lipid bilayer. Thus, improving the absorption and therapeutic efficacy of poorly soluble drugs by enhancing the bioavailability, due to the solubility modification, and rate at which drugs are being released across biological barriers.
Related Knowledge Centers
- Diffusion
- Lipid Bilayer
- Phospholipid
- Sphingomyelin
- Unsaturated Fat
- Cell Membrane
- Model Lipid Bilayer
- Cholesterol
- Saturated & Unsaturated Compounds
- Saturated Fat