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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
To increase the pH value often either CO2 supply is decreased or a base is added. Typically, this base is NaHCO3. Addition of more NaHCO3 to a medium that already contains up to 12 mM will increase the pH sharply (up to 1 log unit). In contrast, with NaHCO3 concentrations exceeding 12 mM, further addition of NaHCO3 will not increase pH significantly anymore. Often, NaOH is used as an alternative for pH control, but it is not well tolerated by many cell lines. Thus, both options should be evaluated at small scale. Intracellular pH is often overlooked but of great relevance for cell physiology. As long as the extracellular pH is above 7.2, the intracellular pH value is typically lower than the extracellular value [54].
Single-Cell Protein Production
Published in Debabrata Das, Soumya Pandit, Industrial Biotechnology, 2021
Growth rate and cell physiology: In continuous cultures, growth rate will be higher, and this relates to a higher RNA/ protein ratio. Therefore, it can easily be said that the growth rate is directly proportional to RNA content. Hence growth level is lowered as a way to suppress nucleic acid. As per the concept of SCP, the biomass should be higher. Thus the method may have only limited importance. Bases such as NaOH or KOH are quickly dissolved, hydrolysing RNA. The extraction of RNA can also be achieved by hot 10% sodium chloride. Cells should be disrupted before the addition of NaOH or KOH. Sometimes protein needs to extract, purified and concentrated.
Microbial Biofilms and Biofilm Reactors
Published in Martin A. Hjortso, Joseph W. Roos, Cell Adhesion, 2018
Brent M. Peyton, William G. Characklis
The influence of bacterial adhesion on cell physiology has not been systematically and consistently defined. It appears as though surfaces do not alter bacterial metabolism and physiology, although this alteration is rarely separated into direct and indirect influences [after a review by van Loosdrecht et al. (75)]. Direct influences are defined as changes in microbial activities resulting from the presence of a surface, e.g., changes in the composition or structure of the cell as a direct result of the adhesion to a surface. These changes may or may not be permanent. Indirect influences include changes in cell activity as a result of (1) changes in the composition of the medium because of substrate adsorption or desorption phenomena at the solid interface, (2) heterogeneity of the space immediately around an attached cell as a result of specific geometry or flow conditions, (3) the fact that cells remain in a particular area after colonizing a surface. Examples of indirect influences are substrate availability or pH changes near the surface. The review concludes that surfaces do influence substrate utilization and yields in both the positive and negative direction; however, the changes are a result of indirect effects, and no conclusive evidence exists to show that adhesion directly affects microbial metabolism or physiology.
Regulation of stem cell fate and function by using bioactive materials with nanoarchitectonics for regenerative medicine
Published in Science and Technology of Advanced Materials, 2022
Wei Hu, Jiaming Shi, Wenyan Lv, Xiaofang Jia, Katsuhiko Ariga
Because cell size and shape can affect cell physiology, cell geometry is established as a biophysical regulator of cell behaviours and fate. Stevens ’s group demonstrates that cell geometry contributes to variety in cytoskeleton networks and thus regulates plasma membrane lipid raft [137]. These biophysical changes trigger activation of Akt/PKB signalling and further regulate cell-geometry-dependent MSC differentiation. Their findings clarify the relationship between cell geometry and stem cell behaviour. Using polymer pen lithography, Cabezas et al. designed nanoscale anisotropic patterned matrix to direct the arranged formation of focal adhesion, which in turn facilitates the most organized cytoskeleton [138]. It is demonstrated that anisotropic focal adhesions increase MSC contractility and direct stem cells different lineage commitment.
An exploration on the toxicity mechanisms of phytotoxins and their potential utilities
Published in Critical Reviews in Environmental Science and Technology, 2022
Huiling Chen, Harpreet Singh, Neha Bhardwaj, Sanjeev K. Bhardwaj, Madhu Khatri, Ki-Hyun Kim, Wanxi Peng
Alkaloids produce toxicity by changing enzyme activity, which affects cell physiology, DNA replication, and DNA repair. Because alkaloids can intercalate with DNA, they can affect the neuromuscular system (Yang & Stöckigt, 2010). There are around 20,000 different alkaloid molecules, and their toxicity and mode of action differ considerably with their structure. For example, pyrrolizidine alkaloids transform themselves into pyrroles to induce the alkylation of DNA and proteins. Moreover, they can induce tumors in humans, along with pulmonary abnormalities and liver damage (Moreira et al., 2018). Quinolone and iso-quinolone alkaloids inhibit cell division and DNA synthesis, whereas the indole-based alkaloids inhibit nucleic acid synthesis by affecting the activity of the dihydrofolate reductase enzyme (Cushnie et al., 2014; Shimshoni et al., 2015). Accidental ingestion of toxic alkaloids can have teratogenic effects through intoxication. Tropane alkaloids have traditionally been used for medicinal and hallucinogenic effects. However, they can also cause weakness in vision, dilation of the pupils, constipation, and poisoning (Afewerki et al., 2019). The common glycoalkaloids solanine and chaconine, isolated from Solanum spp., can cause neurological impairment by inhibiting the activity of acetyl choline neurotransmitters and Ca2+ transport across membranes (Yamashoji & Matsuda, 2013). To protect human and animal health, information about the biochemistry, toxicology, and pharmacology of plant-produced alkaloids is greatly needed.
Effect of ZnO nanoparticles addition to PEO coatings on AZ31B Mg alloy: antibacterial effect and corrosion behavior of coatings in Ringer’s physiological solution
Published in Journal of Asian Ceramic Societies, 2021
Mahya Seyfi, Arash Fattah-alhosseini, Mohammadreza Pajohi-Alamoti, Elham Nikoomanzari
In addition, Figure 9 indicates that the percentage of inhibition of bacterial growth increased by increasing the concentration of nanoparticles from 1 to 4 g/L and increasing the exposing time from 2 to 6 h so that the Z4 specimen had the highest growth inhibition percentage at 6 h for S. aureus (45%) and E. coli (23.5%). As can be seen in Figure 9, in comparison to E. coli (gram-negative bacteria), S. aureus (gram-positive bacteria) seem more susceptible. Higher susceptibility of gram-positive bacteria can be highly related to the differences in the structure of metabolism, degree of contact, cell physiology, or cell wall [60]. Chemical composition is widely accepted that to play a pivotal role in the antibacterial activity of coatings [61]. It is crystal clear that MgO and ZnO can play a major part in bacterial eradication [62,63]. It has been concluded that Zn-embedded coatings can decline bacterial adhesion and prevent bacterial growth by producing reactive oxygen species (ROS) in light or even dark condition and releasing a high concentration of zinc ions [64]. It should be noticed that the content of Zn2+ ion release was tested for 2, 4, and 6 h and no release of Zn2+ ion was seen for all specimens, so the antibacterial mechanism of the coatings does not consider as release-killing.