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Phospholipids and the Clotting Process
Published in E. Nigel Harris, Thomas Exner, Graham R. V. Hughes, Ronald A. Asherson, Phospholipid-Binding Antibodies, 2020
Robert F. A. Zwaal, Edouard M. Bevers, Jan Rosing
In 1961, Bangham27 showed that membranes containing anionic dicetylphosphate express maximal coagulant activity at an optimal net negative surface charge. This observation was subsequently confirmed for phospholipid mixtures composed of phosphatidylserine with phosphatidylcholine or phosphatidylethanolamine.20,28 More recently, the same conclusions were reached on the basis of kinetic studies of coagulation factor activation in model systems. Both Pusey and Nelsestuen29 and van Rijn et al.23 have shown that the complete prothrom-binase complex (cf. Table 1) is maximally active at low mole percentages of phosphatidylserine, while in the absence of the nonenzymatic cofactor Va the membranes have to contain more phosphatidylserine in order to express maximal prothrombin-converting activity.23 It should be mentioned, however, that phosphatidylserine is exceptional among the negatively charged procoagulant phospholipids, in that it retains procoagulant activity even when the phospholipid surface has a net positive charge (vide infraSection VI).
Nature, Function, and Biosynthesis of Surfactant Lipids
Published in Jacques R. Bourbon, Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
The function of the other surfactant phospholipid components, if any, is very unclear. Sphingomyelin can also be compressed to very low surface tensions,86 but in view of its low level in surfactant, its relative importance is questionable. Phosphatidylethanolamine (PE), because of a high liquid-to-crystalline transition temperature, collapses near the equilibrium surface tension; also, the conformation and/or hydration of its cationic head groups does not seem adequate for packing in the metastable state required for very low surface tension.86 PE therefore appears to be a poor surfactant. Nothing is known regarding phosphatidylserine (PS), which is present in extremely low proportion. One must keep in mind that intracellular surfactant (i.e., lamellar bodies) originates from membrane structures and is embedded in membranes and that some “remnants” of typical membrane components, including sphingomyelin, PE, and PS could be co-secreted with typical surfactant phospholipids without presenting any functional significance.
Annexes
Published in Claude Leray, Dietary Lipids for Healthy Brain Function, 2017
Phosphatidylserine (Figure 7.11) is a minor constituent of cell membranes, but the nervous system, especially the white matter, contains large amounts of this phospholipid (up to 18%). One of its features is to have a very unsaturated fatty acid (often DHA) in sn-2 (R2). It can be considered a bioactive lipid, because it is involved in several physiological mechanisms, such as activation of protein kinase C and initiation of blood coagulation.
Preservation of red blood cell antigenicity in a new storage solution in vitro
Published in Annals of Medicine, 2023
Sheng-Hui Tang, Hsin-Chung Lin, Jin-Biou Chang, Yung-Shu Chan, Hui-Fei Tang, Feng-Yee Chang, Tzong-Shi Chiueh, Bing-Heng Yang
The few studies addressing in vitro RBC preservation have used only antibiotics and antioxidants in Alsever’s solution [4]. One study employed antioxidant additives and measured RBC storage survival based on phosphatidylserine exposure and haemolysis. The results revealed that a mixture of natural antioxidants provided a slight, although significant, decrease in phosphatidylserine exposure. No significant decrease in haemolysis was noted in the high haematocrit group, and phosphatidylserine exposure was only effective in the low haematocrit group [4]. Several microorganisms can induce haemolysis [5,6]; therefore, antibiotics such as cycloheximide [7], penicillin, streptomycin [8], neomycin sulphate, and chloramphenicol are added to Alsever’s solution [9]. The addition of cycloheximide caused negligible antigen deterioration after 8 weeks of storage, but the study did not evaluate the extent of haemolysis [7].
Mesoporous tantalum oxide nanomaterials induced cardiovascular endothelial cell apoptosis via mitochondrial-endoplasmic reticulum stress apoptotic pathway
Published in Drug Delivery, 2023
Yuanyong Jiao, Xiwei Zhang, Hongyu Yang, Hao Ma, Junjie Zou
Atherosclerosis, the primary etiology of CVD, continues to be a leading cause of death worldwide (Nichols et al., 2014). Tricot et al. found that 60% of studied lesions showed endothelial apoptosis (Tricot et al., 2000). The endothelial cells underwent rapid necrotic cell death within minutes after being treated with PEG@mTa2O5, as revealed by Napierska et al. (Napierska et al., 2009). Subsequent research by Liu and Sun found that PEG@mTa2O5 significantly caused apoptosis in HCMECs at concentrations as low as 50 g/mL. In this case, the induction of apoptosis by PEG@mTa2O5 was validated both by morphological observation of apoptotic cells and by quantitative analysis of their numbers (Wang et al., 2018). Phosphatidylserine exposure, an early apoptotic indication, was readily apparent even at the lowest dosage (12.5 µg/mL, 24-h, Figure 4). Endothelial apoptosis was induced by PEG@mTa2O5 in a dose- and size-dependent fashion. Developing endothelial apoptosis after exposure to PEG@mTa2O5 may be a significant biological consequence in this setting and may harm the cardiovascular system. However, a thorough understanding of the underlying processes remains elusive (Liu & Sun, 2010).
Assessment of the Anti-inflammatory Effects of NORFLO® ORO in Acute Relapses of HLA-B27-associated Autoimmune Uveitis: A Multicenter, Randomized, Placebo-controlled, Double-blind Clinical Study
Published in Ocular Immunology and Inflammation, 2023
Pia Allegri, Luca Cimino, Janet L. Davis, Ilknur Tugal-Tutkun
In recent studies, curcumin, also known as diferuloylmethane, a natural bioactive extract derived from the roots of a plant (Curcuma longa), has shown its potential activity to scavenge free radicals, also known as the reactive oxygen species (ROS), thereby acting as an antioxidant and anti-inflammatory agent.13–16 It has poor systemic bioavailability due to its low hydrosolubility and rapid metabolization.17 A patented formulation (Iphytoone®) enhances the absorption of curcumin and increases its selectivity to eye tissues. Iphytoone® contains a blend of curcuminoids (curcumin, demethoxycurcumin and bisdemethoxycurcumin), which are dispersed in an innovative double-layer of phospholipids, including phosphatidylcholine and phosphatidylserine. The phosphatidylserine is a vehicle for the release of the active ingredient in a more efficient and bioavailable way and it is also an active part of the treatment. Iphytoone®, which is a phospholipidic-curcumin complex (PHBC) resembles the lipid membrane of cells, and this characteristic enhances its cellular selectivity and protects curcuminoids from degradation. After oral administration, PHBC rapidly metabolizes allowing curcumin absorption within minutes.13–19 Recent studies showed its beneficial effects in ocular and retinal diseases including age-related macular degeneration, glaucoma and diabetic retinopathy; it has been proposed as a promising therapeutic option in various inflammatory eye diseases.20–25