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Introduction to the Biological System
Published in Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu, Interdisciplinary Engineering Sciences, 2020
Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu
Biochemically, a cell membrane is composed of lipids (40%), proteins (55%), and carbohydrates (5%). The lipid bilayer of the plasma membrane makes it semi-permeable which regulates the passage of molecules, ions, and water (Figure 8.2). The bilayer structure also prevents these substances to enter the cytosol to maintain internal conditions. The cell surface receptor proteins play an important role in cell–cell interactions or cell–material interactions. The biological membranes can be best described as a phospholipid bilayer with several transmembrane proteins and voltage-gated ion channels. Such membrane physically separates intracellular organelles from the cytoplasm and a cell from the extracellular matrix.
Role of Dendrimers in the Development of New Dendritic Cells Immunotherapies Against HIV-1 Infection
Published in Anne-Marie Caminade, Cédric-Olivier Turrin, Jean-Pierre Majoral, Phosphorus Dendrimers in Biology and Nanomedicine, 2018
Rosa Reguera, Joao Rodrigues, Jose Correa, M. Angeles Munoz-Fernandez
Different cell-surface molecules expressed by DCs are being explored as targets to deliver antigens in vivo, such as the C-type lectin mannose receptor, CD205, and DC-specific intercellular adhesion molecule 3 (ICAM3)-grabbing non-integrin (DC-SIGN) [127–132]. The outcome of the in vivo DC-based therapy will be influenced by intracellular routing of the targeted receptor. Specific cell-surface receptors trigger distinct intracellular signaling pathways on ligand binding, thereby modulating immune responses. Moreover, what density of ligand should be arrayed on the nanoparticles surface to interact most efficiently with DC is an open question that must be evaluated.
Dynein in Endosome and Phagosome Maturation
Published in Keiko Hirose, Handbook of Dynein, 2019
Ashim Rai, Divya Pathak, Roop Mallik
Cells interact with their environment in diverse ways. Molecules present in the extracellular environment can bind to cell surface receptors and initiate signaling cascades inside the cell. Apart from cell signaling, uptake of extracellular material is perhaps a very important mode of communication of cells with their extracellular milieu. This can occur in the form of two pathways that are fundamentally similar, but also subtly different from each other. Uptake of fluids and small particles occurs through the endocytic pathway, whereas particles >500 nm in size (e.g., bacteria) are taken up through the phagocytic pathway [39]. These pathways are crucial for diverse cellular processes, ranging from nutrient acquisition in lower organisms to pathogen degradation by cells of the immune system in higher organisms. In both endocytosis and phagocytosis, extracellular material binds to cell surface receptors and initiates signaling, this then leads to actin polymerization and the formation of membrane extensions (pseudopods) which engulfs the extracellular material. Pinching of the engulfed particle from the plasma membrane leads to formation of the endosome/phagosome. After a brief period of myosin-driven movements on cortical actin, the endosome/phagosome is transferred to microtubules wherein the long-range transport and maturation of these compartments occurs. During the “early” phase of maturation, the endosome/phagosome undergoes extensive “kiss and run fusion” with other vesicles. This is crucial to acquire the set of lipids and proteins necessary for endosome/phagosome maturation and transport [18, 42]. The early phase of maturation is also marked by progressive acidification of the endosomal/phagosomal compartment through ATP-dependent proton pumps present in the membrane.
Atmospheric environment and severe acute respiratory infections in Nanjing, China, 2018–2019
Published in International Journal of Environmental Health Research, 2023
Kang-Jun Wu, Xiao-Qing Wu, Lei Hong
Air pollution causes increased mortality from cardiovascular disease, chronic obstructive pulmonary disease, and acute respiratory infections, with 7 million premature deaths per year attributed to air pollution worldwide (WHO 2018). PM10 and PM2.5 have similar effects above 100 μg/m3. The Lag risk of high PM was greater and earlier than that of the low. PM plays two main roles in the transmission of respiratory pathogens: (1) it contributes to the transmission of pathogens as a carrier of pathogens; (2) it acts as an antigenic complex to strengthen the activity of intrinsic immune cells in the respiratory tract, forming adaptive immunity (Farhangrazi et al. 2020). In addition, inhalation of enormous amounts of particulate matter causes cellular damage in the lung and may cause upregulation of cell surface receptor expression of related pathogens, promoting pathogen replication. Thus, it enhances pathogen colonization in the respiratory (Dolci et al. 2018; Mishra et al. 2020; Sagawa et al. 2021).
Epidemiology, virology and clinical aspects of hantavirus infections: an overview
Published in International Journal of Environmental Health Research, 2022
Sima Singh, Arshid Numan, Dinesh Sharma, Rahul Shukla, Amit Alexander, Gaurav Kumar Jain, Farhan Jalees Ahmad, Prashant Kesharwani
Following attachment to a cell surface receptor, the Hantavirus virus is incorporated into the host population. After binding, cell entry is mediated through clathrin-coated pits, and virons are eventually delivered to lysosomes. Virions are uncoated inside the endolysosomal compartment, and three viral capsids are released into the cytoplasm (Jin et al. 2002). This causes the virus to be taken up by a clathrin-coated vesicle (CCV), which is made up of clathrin-coated cellular membrane (Ramanathan and Jonsson 2008). RdRp initiates transcription and produces three mRNAs, one from each S, M, and L section of the viral RNA. The S and L derived mRNAs are translated on free ribosomes. Although M-specific mRNAs are translated on the rough endoplasmic reticulum (ER). Intrinsically, the glycoprotein precursor is cleaved at a closely conserved amino acid motif, yielding two glycoproteins, Gn and Gc (Spiropoulou 2000). The glycoproteins Gn and Gc are transferred to the Golgi complex for glycosylation. Following glycosylation in the ER, Gn and Gc transfer to the Golgi complex. Hanta virions are assumed to form in the Golgi complex. It is accompanied by budding into the Golgi cisternae, migration to the plasma membrane of secretory vesicles, and exocytosis. However, the specifics of virion egress mostly remain unknown (Szabó 2017).
Influence of extracellular cues of hydrogel biomaterials on stem cell fate
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Haley Barnett, Mariya Shevchuk, Nicholas A. Peppas, Mary Caldorera-Moore
Hydrogel properties can be tuned to regulate stem cell behavior through both cell-matrix and cell-cell interactions. Hydrogel properties such as stiffness and viscoelasticity will affect cell-matrix interactions through the process of mechanotransduction, where cells transduce a physical stimuli into biochemical signals. There have been numerous studies demonstrating that the stiffness and viscoelastic properties of a hydrogel can alter a cell’s attachment rates [36], cell spreading [44], proliferation efficiency [45,46], and differentiation potential [28]. Hydrogel stiffness is typically controlled through crosslinking density by varying the concentration of polymer or crosslinking molecule and has been varied to achieve elastic moduli of tissues ranging from brain (0.1–1 kPa) to bone (∼100 kPa) [28]. Other tunable properties of hydrogels, such as porosity and degradation, have been demonstrated to influence cell-cell interactions [47,48]. Cell-cell interactions, whether they occur through direct cell surface receptor interactions or paracrine signaling, aid in controlling cell function [49]. Therefore, it is important to consider these properties when designing a hydrogel scaffold as changes in cell-matrix and cell-cell interactions will influence a cell’s decision to attach, proliferate or differentiate. This highlights the importance of material selection when designing a hydrogel for tissue engineering applications, as different polymers can impart different biological, mechanical, and degradative properties to the hydrogel. A brief overview of polymers used for hydrogels are discussed below.