Here, we have studied the setup of an integrated bioprocess for the production of artificial Malaria vaccine candidates with Pichia pastoris. Production of pharmaceutically relevant proteins such as vaccines has high demands regarding protein processing in the bioreactor and for subsequent purification. To implement this challenging protein expression process, a highly instrumented bioreactor was configured for repeated fed batch cultivations and supplemented with an at‐line monitoring of the target protein production via HPLC. The integration of a fast in situ purification of the sensitive products using an expanded bed adsorption for a sequential integrated bioprocess allows cyclic product separation. Thus, a fully automated production of artificial malaria vaccines was achieved.
J. Neurochem. (2010) 113, 735–748.
Abstract
Disruption of brain energy metabolism is the hallmark of cerebral ischemia, a major cause of death worldwide. Astrocytes play a key role in the regulation of brain metabolism and their vulnerability to ischemia has been described. Aiming to quantify the effects of an ischemic insult in astrocytic metabolism, primary cultures of astrocytes were subjected to 5 h of oxygen and glucose deprivation in a bioreactor. Flux distributions, before and after ischemia, were estimated by metabolic flux analysis using isotopic information and the consumption/secretion rates of relevant extracellular metabolites as constraints. During ischemia and early recovery, 30% of cell death was observed; several metabolic alterations were also identified reflecting a metabolic response by the surviving cells. In the early recovery (∼10 h), astrocytes up‐regulated glucose utilization by 30% and increased the pentose phosphate pathway and tricarboxylic acid cycle fluxes by three and twofold, respectively. Additionally, a two to fivefold enhancement in branched‐chain amino acids catabolism suggested the importance of anaplerotic molecules to the fast recovery of the energetic state, which was corroborated by measured cellular ATP levels. Glycolytic metabolism was predominant in the late recovery. In summary, this work demonstrates that changes in fluxes of key metabolic pathways are implicated in the recovery from ischemia in astrocytes.
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