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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
It has been postulated that the phase preference of lipid molecules in the lipid-water system is related to their molecular shapes or geometries.40 Diacyl PC molecules in the Lα phase are cylindrical in shape. Their headgroup areas at the lipid-water interface are equivalent to the sum of the cross-sectional areas for the two acyl chains near the methyl termini. These cylindrical phospholipid molecules energetically favor to adopt the planar lamellar structure. Natural PEs, however, are wedge-shaped molecules in which the headgroup area at the lipid-water interface is less than the sum of the cross-sectional areas of the two acyl chains near the methyl termini due to the presence of unsaturated ds-double bonds in the sn-2 acyl chain. These wedge-shaped molecules prefer to self-assemble into structures of high surface curvature such as the H„ phase rather than into planar lamellar structure.
Pathophysiological overview of M-SHRSP
Published in H. Saito, Y. Yamori, M. Minami, S.H. Parvez, New Advances in SHR Research –, 2020
Hiroyuki Ito, Tsuneyuki Suzuki
To elucidate the mechanisms of such severe arterial changes, electron- microscopic observations were carried out for the aorta or mesenteric artery of M-SHRSP. In the scanning electronmicrographs, the endothelial surface was very irregular with many nuclear protrusions. Cauliflower-like blebs and/or crater-like holes were frequently seen in endothelial cells (Fig. 3a). In a high-power view, many microvilli were visible on the surface of the cells. These changes were not observed at a prehypertensive stage or in endothelial cells of normotensive WKY. In the transmission electronmicrographs, severe intimal changes were found in the M-SHRSP aorta and mesenteric artery. Marked vacuolic changes were recognized in endothelial cells and many microvilli were found (Fig. 4a). The subendothelial space was wide and edematous. In some instances, basement membrane-like materials were recognized as a lamellar structure. Medial smooth muscle cells became irregular in shape with process-like protrusions of the plasma membrane toward the gaps of the internal elastic membrane. Occasionally, migration of medial smooth muscle cells into the intima was observed in the mesenteric artery, showing intimal thickening (Fig. 4b). Such destructive changes in the arterial wall were frequently found in the M-SHRSP mesenteric artery rather than in the aorta.
Lipid-Based Nanoparticles: SLN, NLC, and MAD
Published in Madhu Gupta, Durgesh Nandini Chauhan, Vikas Sharma, Nagendra Singh Chauhan, Novel Drug Delivery Systems for Phytoconstituents, 2020
Rita Cortesi, Paolo Mariani, Markus Drechsler, Elisabetta Esposito
A recent study conducted by Rosseto et al. (2017) investigated lipid-based nanoparticles (i.e., SLN and NLC) loading propolis extract or by-products for cutaneous application. After production of SLN and NLC using the stirring/ultrasonication method, nanoparticles were analyzed by means of cryo-TEM and X-ray diffraction spectroscopy. It was found that both NLC and SLN displayed homogenous distribution and various shapes resembling dark needles or elongated flat particles. Moreover, NLC showed a more elongated shape than SLN, confirming the effect of the presence of the oil tricaprylin (Esposito et al., 2008, Jores et al., 2004, Ravani et al., 2015). Morphology differences were not evident between the unloaded and loaded propolis extracts. In some samples, the internal lamellar structure give rise to a structure called “sandwich” corroborating with other works of this same research area (Ravani et al., 2015).
A tale of nucleic acid–ionizable lipid nanoparticles: Design and manufacturing technology and advancement
Published in Expert Opinion on Drug Delivery, 2023
At endosomal acid pH, ionizable lipids bind with anionic endosomal member lipids and transfer nucleic acid into the cytoplasm (Figure 3) [27,28]. As shown in Figure 3, the amine head group of ionizable lipids is not protonated at neutral physiological pH. The tail of the lipid also preserves the cylindrical form with the head group. But at low endosome pH, however, the amine head group becomes positively charged and begins to interact with the negatively charged endosomal membrane. The linear bilayer structure of the endosome is transformed into a no-bilayer, hexagonal (HII) structure with an inverted cylindrical shape by this interaction [29]. The deformation of the endosomal membrane allows nucleic acid to enter the cell without denaturation. The mechanism of endosomal escape by ionizable LNPs is determined by the shape and branching of the ionizable lipids. Smaller polar head groups and long unsaturated hydrophobic tails allow for faster lipid transfer from lamellar to hexagonal phase, whereas large polar head groups and saturated hydrophobic tails adopt a more stable lamellar structure. Ionizable lipids also improve electrostatic interactions between anionic nucleic and cationic lipids, increasing nucleic acid loading and stability.
Studies on the Effectiveness of Ozone Therapy on the Treatment of Experimentally Induced Keratitis with Candida albicans in Rabbits
Published in Seminars in Ophthalmology, 2022
Kemal Varol, Ayşe Nedret Koç, Latife Çakır Bayram, Hatice Arda, İhsan Keleş, Metin Ünlü, Vehbi Güneş, Gencay Ekinci, İlknur Karaca Bekdik, Mustafa Altay Atalay
On light microscopic examination, the cornea was observed to consist of five layers. Basal columnar cells, intermediate polygon cells, and superficial squamous cells were present in the multi-layer squamous nonkeratinized layer. Under the corneal epithelium (Bowman’s layer). Secondary propria consisted of collagen fibers and scattered spindle-shaped stromal cells arranged at regular intervals. The Descemet membrane was present just below the stroma and was covered by the endothelium of Descemet. Normal corneal morphology was observed in the negative control group. In this group, the lamellar structure of the stroma was regular. There was no change in the size and shape of the corneal epithelial cells. Keratocytes are neatly sorted. Keratin is not available (Figure 2. A.1).
Distribution of Aquaporin-4 channels in hippocampus and prefrontal cortex in mk-801-treated balb/c mice
Published in Ultrastructural Pathology, 2022
Omer Burak Ericek, Kübra Akillioglu, Dilek Saker, Ibrahim Cevik, Meltem Donmez Kutlu, Samet Kara, Dervis Mansuri Yilmaz
The nerve cell bodies in the gray matter, myelin-free nerve fibers, and glial cells, as well as the myelinated axons in the white matter, and the fine structures of the glial cells, were evaluated in the electron microscopic examination of the tissue samples of prefrontal cortex in the control group treated with normal saline. The nerve cell perikaryon in the gray matter was found to consist of a centrally located nucleus and a perinuclear cytoplasm surrounding it. The spherical cell nucleus was in the center of the cell. There was a well-distinguishable nucleolus in the vesicular-type nucleus. The mitochondria in the neuron cytoplasm were either ovoid or round-shaped and had both transverse and longitudinal-type cristae. The Golgi complex with the perinuclear settlement was observed in large numbers scattered throughout the perikaryon Neuroglial cells settled in the prefrontal cortex were generally found to have a spherical or ovoid nucleus and a perinuclear thin cytoplasmic ring surrounding the nucleus. In myelinated nerve fibers, it was observed that the myelin sheath had a regular lamellar structure. In axon cytoplasms, mitochondria, several neurotubules, and neurofilaments were remarkable (Figure 10(a-c)).