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Role of Tumor Cell Membrane in Hyperthermia
Published in Leopold J. Anghileri, Jacques Robert, Hyperthermia In Cancer Treatment, 2019
Since the cell membrane is a heterogeneous system, hyperthermia damage might be limited only to specific areas.140 Considering the high activation energy needed for cell injury and death, the primary effect of heat may be a thermotropic transition of some cellular component.141 Contrary to microorganisms which reached clinical hyperthermia values of 41 to 45°C and showed no evidence of a phase transition, mammalian cells, which at normal physiologic temperature present the bulk of plasma membrane lipid as a liquid crystalline phase, are quite susceptible to a change in physical state. It is likely that due to functional need, some critical fraction is in the gel state. If the temperature is increased, this critical fraction might melt, and the change of physical state could lead to a functional loss and probably affect cell survival. Contrary to this, microorganisms heated to clinical hyperthermia values show no evidence of such a phase transition.142–144
FT-IR Studies of Molecular Conformation in Biological Membranes
Published in R. Michael Gendreau, Spectroscopy in the Biomedical Sciences, 1986
David G. Cameron, Richard A. Dluhy
As an empirical measurement correlated with the conformation of the lipid acyl chains, the frequency of the antisymmetric CH2 stretching band at 2920 cm-1 or the symmetric stretching band at 2850 cm−1 has been extensively used to monitor the effects of ions, cholesterol, and membrane proteins on lipid conformation.9,23–26 Pure, saturated, synthetic phosphatidylcholine (PC) model membranes have been the most extensively studied of the compounds used as membrane models. The thermotropic behavior of these phospholipids has been examined by FT-IR.27 The detailed temperature profiles of the frequency of the 2920 or 2850 cm−1 infrared bands show discontinuities that correlate with the corresponding calorimetric phase transition for the particular lecithin under study; hence, these parameters can monitor the average conformational order of the system.
Structures and Properties of Self-Assembled Phospholipids in Excess Water
Published in E. Nigel Harris, Thomas Exner, Graham R. V. Hughes, Ronald A. Asherson, Phospholipid-Binding Antibodies, 2020
Also playing an important role in the thermotropic phase behavior of the lamellar phospholipids is the intramolecular linkage between the hydrocarbon chain and the glycerol backbone. For instance, if the two carbonyl groups in C(16):C(16)PC are replaced by two methylene units, the resulting compound, l,2-dihexadecyl-sn-3-phosphocholine (DHPC), is an ether-linked analog. Significant differences are observed in the thermotropic behavior of this analog.63 In the fully hydrated state, four thermotropic phases are detectable, with readily reversible thermal transitions at 5, 32.5 and 43.6°C.64 Below the pretransition temperature of 32.5°C, the acyl chains of DHPC are all fully interdigitated.63,64 The low-temperature transition of 5°C can be designated as the interdigitated crystalline to the interdigitated gel phase transition. The middle-temperature transition at 32.5°C is the interdigitated gel → the noninterdigitated Pβ, gel phase transition, and the high-temperature transition at 43.6°C corresponds to the Pβ, Lα phase transition. Clearly, only the high-temperature transition resembles the main phase transition of the diester C(16):C(16)PC bilayer. The physical basis for the full chain interdigitation in DHPC bilayers at temperatures below 32.5°C is not known. However, the oxygen of the saturated ether moiety of DHPC is effectively charged because of the greater electronegativity of oxygen than of carbon. If the initial segments of the two ether-linked hydrocarbon chains adopt the conformation similar to that of SPM as shown in Figure 4, one can thus speculate that the effective charge density at the level of ether oxygens might be diluted by the presence of chain methyl termini from the opposing leaflet due to the full interdigitation of the long hydrocarbon chains in the bilayer. Consequently, the charge-charge repulsion between two all-trans chains near the interface region would be diminished considerably, making the DHPC bilayer more stable at low temperatures.
Phytosterol-loaded CD44 receptor-targeted PEGylated nano-hybrid phyto-liposomes for synergistic chemotherapy
Published in Expert Opinion on Drug Delivery, 2020
Milan Gautam, Raj Kumar Thapa, Biki Gupta, Zar Chi Soe, Wenquan Ou, Kishwor Poudel, Sung Giu Jin, Han-Gon Choi, Chul Soon Yong, Jong Oh Kim
FT-IR spectroscopic analyzes of individual lipids, polymers (Figure S3a–d), free drugs, blank liposomes, DOX-STS-lipo, and HA-DOX-STS-lipo were performed. As depicted in Figure 3(d), the characteristic peaks of HA were observed at 3270 cm−1 (O-H and N-H stretching); 2890 cm−1 (C-H stretching of CH2 and CH3 groups); and 1617 and 1401 cm−1 (C = O and C-O of carboxyl groups) in HA-DOX-STS-lipo, suggesting successful coverage with HA on the liposomal surface [3]. We further characterized the nature of drug incorporation using XRD analysis. The XRD diffractogram showed numerous sharp and intense peaks of DOX at 2θ scattered angles of 12.8°, 14.6°, 16.1°, 17.5°, 18.9°, 20.5°, 22.1°, 25.6°, and 30.2°, reflecting its high crystallinity (Figure 3(e)). While, these sharp peaks were almost vanished in HA-DOX-STS-lipo diffractograms, suggesting that the drugs were molecularly dispersed and in an amorphous state. DSC analyzes were conducted to investigate the thermotropic properties of the hybrid phyto-liposomes. The DSC thermograms showed characteristic sharp peaks of DOX and STS corresponding to their respective melting points at 207.22 and 168.49°C, respectively (Figure 3(f)). However, the sharp peaks were absent and broader peaks were observed in HA-DOX-STS-lipo, suggesting that both drugs were well encapsulated within the hybrid phyto-liposomal carriers in the amorphous state.
Panax ginseng root, not leaf, can enhance thermogenic capacity and mitochondrial function in mice
Published in Pharmaceutical Biology, 2020
Su-hui Wu, Han-bing Li, Gen-Lin Li, Yue-juan Qi, Juan Zhang, Bai-yan Wang
The cold or hot properties of herbal drugs are very important in Traditional Chinese Medicine (TCM) that has a long-standing tradition of nearly 4000 years. Numerous scientists have explored these properties from the aspect of endocrinological, immunological, neurological (Li et al. 1999), and thermodynamic aspects (Zhao et al. 2011). Since the concept of thermodynamics was proposed, it has become an important research topic among scientists. Previous thermodynamics studies focussing on the thermogenesis of animals have observed the thermotropism behaviour in Kunming mice with cold or hot syndrome under different circumstances. Their results suggested that the traditional ‘cold’ drug Coptidis could acutely decrease the energy metabolism and regulate animals’ response in preferring a warm environmental temperature. Meanwhile, the cold or hot drugs could change oxygen consumption, liver SOD activity, ATPase activity in mice (Zhao et al. 2011) and serum creatine kinase in rat, which suggest that these observations were related to the impact of herb medicine to energy metabolism (Zhang et al. 2009). In this paper, we investigated certain thermogenic parameters at tissue and cellular level to examine the essence of cold or hot properties.
Incorporation of PEGylated δ-decalactone into lipid bilayers: thermodynamic study and chimeric liposomes development
Published in Journal of Liposome Research, 2020
Natassa Pippa, Athanasios Skouras, Nikolaos Naziris, Francesca Biondo, Mattia Tiboni, Hector Katifelis, Maria Gazouli, Costas Demetzos, Luca Casettari
The most promising chimeric systems, in terms of thermotropic behaviour, were chosen to be developed as liposomes. Based on the enthalpy of the main transition, those were DSPC:polymer 9:0.5. The physicochemical properties of the developed chimeric lipid/polymer nanosystems are presented in Table 5. These include the particle size (Dh), polydispersion index (PDI), zeta potential (ζ-pot) and scattered light intensity (I). In addition, Figure 3 provide the physical stability studies of the systems. All the formulations were developed in PBS solution since this medium simulates well the physiological environment in terms of pH (7.4) and ionic strength (Pippa et al.2014).