Culture protecting agent

Among the possible additives that can increase medium viscosity with no apparent detrimental effects on the cells, dextran (up to 0.3%, w/v) has been found beneficial to these cultures. A limited number of experiments have shown that MCs and CMCs are not suitable protective agents because they cause microcarrier aggregation and flotation (i.e. collection on the liquid surface in the form of aggregates). 

Properties and functions. Due to their high viscosities, the G. serve as lubricants and protective agents, e.g. against proteolytic enzymes, bacteria and viruses They play a role in cellular adhesion and contact inhibition of cell growth in tissue culture. They are also responsible for cellular recognition of foreign tissue. 

Both brain tissue slice preparation and dissociated primary cultures of brain cells are convenient models to investigate the functions of ascorbic acid in the nervous system. These systems lose their ascorbic acid when they are incubated in ascorbic acid-free media, thus affording models of scurvy. In both preparations, ascorbic acid has been proposed to be a protective agent against several forms of brain insult. 

Ever since the introduction of levodopa there have been concerns that it may be neurotoxic, particularly towards neurons in the substantia nigra, which are in any case depleted in Parkinson s disease. There is a plausible mechanism for this, through generation of free radicals. The evidence from cell culture studies, animal studies, and clinical data has been reviewed, and the authors concluded that the culture experiments are confounded by lack of ascorbate in the medium, which would act as an important protective agent, as it appears to do in vivo in animals, notably in primates [95 ]. The clinical data have failed to support the idea that levodopa accelerates striatal neuronal loss. However, the evidence is contradictory, and it seems unlikely that even after 50 years we shall get a definitive answer. 

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