China
Africa
Explore chapters and articles related to this topic
Upstream processing for viral vaccines–General aspects
Published in Amine Kamen, Laura Cervera, Bioprocessing of Viral Vaccines, 2023
Lars Pelz, Sven Göbel, Karim Jaen, Udo Reichl, Yvonne Genzel
Media formulation is additionally constrained to osmolality. The osmolality of the medium refers to “the concentration of osmotically active particles in that solution” [40]. Human blood plasma has an osmolality of approximately 290 mOsmol/kg. To mimic physiological conditions, cell culture media are adjusted to values of 260–330 mOsmol/kg. However, most continuously growing mammalian cells can show a very wide tolerance up to 500 mOsmol/kg [41]. Yet, cells will react to the respective osmolality of the medium by either shrinking (hyperosmotic, >330 mOsmol/kg) or swelling (hypoosmotic, <260 mOsmol/kg). During the cultivation, osmolality is changed by addition of salts, release of metabolites (lactate), feeding, and addition of buffers. Furthermore, monitoring of the osmolality can be very useful as quality control of the medium or to verify consistency between lots. Moreover, determination of cell size/cell volume via cell counter or capacitance probes should consider that cells do not only change in diameter due to osmolality, but also due to cell cycle phase, metabolic state or cell lysis (virus production).
Interconnection between PHA and Stress Robustness of Bacteria
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Stanislav Obruca, Petr Sedlacek, Iva Pernicova, Adriana Kovalcik, Ivana Novackova, Eva Slaninova, Ivana Marova
To defend against the harmful effect of osmotic fluctuations, bacterial cells, regardless of their salinity preferences, developed sophisticated protective mechanisms. Bacterial cells are able to detect the variances in external osmotic pressure by the action of various membrane-associated mechanosensitive channels and osmotic transporters. The osmosensing capability enables cells to react to fluctuations in osmolarity. The exposure of the cells to osmotic up-shock induces the synthesis of osmolytes (also called compatible solutes). These small organic molecules such as trehalose, ectoines, glutamate, glycine betaine, etc. compensate the extracellular osmotic pressure and therefore protect bacterial cells from the harmful effect of osmotic up-shock. Apart from their balancing function, these small molecules also act as chemical chaperones and therefore protect various sensitive biomolecules from denaturation and loss of biological activity [58]. When the opposite situation occurs and cells are introduced into a hypotonic environment, water as well as osmolytes are pumped out of the cells by so-called “mechanosensitive channels” to protect the cell from hypotonic lysis [59,60].
Fundamentals of Receptor Assessment
Published in Jack Daugherty, Assessment of Chemical Exposures, 2020
Tissue fluid osmolarity typically measures around 300 mOsm. Osmolarity is the concentration of an osmotic solution, measured in milliosmols. Hypoosmolar aerosols are believed to cause bronchoconstriction. The dose of acid fog inhaled is expressed as total hydrogen ion (H+TOTAL): HTOTAL+=[H+]×{(tQB)(VE(QB))+(tEx)(VE(Ex))}
Carbon-based nanomaterials as scaffolds in bone regeneration
Published in Particulate Science and Technology, 2020
Liana Crisan, Bogdan Vasile Crisan, Simion Bran, Florin Onisor, Gabriel Armencea, Sergiu Vacaras, Ondine Patricia Lucaciu, Ileana Mitre, Mihaela Baciut, Grigore Baciut, Cristian Dinu
The factors that govern differentiation toward osteoblastic line such as adhesion and signals received from the extracellular matrix can decisively influence remodeling of bone and, ultimately, the ability of these cells to integrate into biomaterials used in reconstructive surgery. Creation of three-dimensional matrix represents an important step in transplantation, these materials providing an area that favors attachment, survival, proliferation, differentiation of stem cells and osteoblastic line progenitors. In addition, these 3D structures allow for the development of vascularization, new tissue formation, and thus may be reshaping. At the moment there are many materials used in transplantation, the differences being related to 3D architecture, volume, porosity, mechanical properties, osmolarity and pH, biocompatibility, and biodegradation properties. Cells, in turn, represent an important component of the process of transplanting, they represent the dynamic and integrative element of the graft.
HEMA and alginate-based chondrogenic semi-interpenetrated hydrogels: synthesis and biological characterization
Published in Journal of Biomaterials Science, Polymer Edition, 2020
María Luz Torres, Tamara Gisela Oberti, Juan Manuel Fernández
Cartilage is 75% water, and because it is an avascular tissue, its viability depends on the diffusion of oxygen and nutrients through it [2]. Hydrogels are polymeric networks that have a great water retention capacity and their properties have attracted attention to be applied as scaffolds and drug delivery systems [25]. For this reason, we have studied the swelling capacity of the hydrogels obtained in this work. In the literature, there are many studies that have evaluated the swelling capacity of hydrogels in water. However, since the objective of our materials is to be used in the regeneration of cartilage, we believe that it is more representative to perform swelling studies in PBS instead of water, because its osmolarity (isotonic) and ion concentration (PO4−2, Cl-, Na+, and K+) are very similar to that of the extracellular fluid of different mammals. In this way, we demonstrate that, in order to perform better extrapolations of in vitro results to in vivo predictions, it is not enough to know the swelling of biomaterials in water. Studies should be carried out in conditions that resemble the physiological situation as closely as possible.
Using chemical chaperones to increase recombinant human erythropoietin secretion in CHO cell line
Published in Preparative Biochemistry and Biotechnology, 2019
Mehri Mortazavi, Mohammad Ali Shokrgozar, Soroush Sardari, Kayhan Azadmanesh, Reza Mahdian, Hooman Kaghazian, Seyed Nezamedin Hosseini, Mohammad Hossein Hedayati
Betaine was a unique case, which was associated with no increase in ER size yet a slight enhancement in the expression of ER chaperones. It exhibited the greatest increase in EPO productivity with a low concentration (3 mM). Betaine treatment increased specific productivity from 162 µIU/cell/day for untreated cells to 365 µIU/cell/day. In the literature also, there are reports that betaine supplementation also increases FVIII secretion.[34] Previously osmoprotective effect of betaine in a high concentration (15 mM) has been reported to increase specific productivity of thrombopoietin with significant decrease in cell growth because of high osmolarity.[35] In this study, 3 mM betaine is used in 5-fold lower concentration with a low effect on cell survival rate with a significant increase in specific EPO productivity. It could be due to specific effect of betaine on EPO folding and protecting it to increase its secretion better than the other chemicals as it is reported previously.[36] This specific action of chemicals has been also previously reported for glycan as a specific and stabilizing ligand for CFTR.[37]