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Background: Intracerebroventricular (ICV) administration of streptozotocin (STZ) has been used as a metabolic model of sporadic Alzheimer's disease (AD). Erythropoietin (EPO) possesses neuroprotective and memory‐improving effects, which might be advantageous in treating different characteristics of AD. Nevertheless, the hematopoietic effect of EPO has hindered its application as a neuroprotective agent. Previous studies have shown that a new Epo derivative called carbamylated Erythropoietin‐Fc (CEPO‐Fc), yield noticeable neuroprotective effects without affecting hematopoiesis. In this study, the neuroprotective effects of CEPO‐Fc on icv‐STZ induced memory impairment and hippocampal apoptosis were examined. Method: Adult male Wistar rats weighing 250‐300 g were used. STZ was administered on days 1 and 3 (3 mg/kg in divided doses/icv), and CEPO‐Fc was administered at the dose of 5000 IU/ip/daily during days 4‐14. The animals were trained in Morris water maze during days 15‐17, and the memory retention test was performed on the 18th day. Following behavioral studies, the animals were sacrificed and their hippocampi isolated to determine the amounts of cleaved caspase‐3 (the landmark of apoptosis). Result: The results showed that CEPO‐Fc treatment at the dose of 5000 IU/kg/ip was able to prevent the learning and memory deficit induced by icv‐STZ. Western blot analysis revealed that STZ prompted the cleavage of caspase‐3 in the hippocampus while pretreatment with CEPO‐Fc significantly reduced the cleavage of this protein. Conclusion: Collectively, our findings suggest that CEPO‐Fc could restore STZ‐induced learning and memory impairment as well as apoptosis in the hippocampal region in a rat model of sporadic AD induced by icv‐STZ. [ABSTRACT FROM AUTHOR]

Different feeding strategies for the production of human interferon-gamma using an isopropyl beta-D-thiogalactoside-inducible expression system in recombinant Escherichia coli BL21(DE3) (plasmid pET3a-ifngamma) were studied. Four fed-batch modes were designed to compare the effect of mu (specific growth rate) on recombinant-protein production, substrate consumption, by-product formation and plasmid stability during pre- and post-chemical induction in high-cell-density cultures of E. coli. It was found that Y(p/s), the product/substrate yield of interferon-gamma was significantly affected by mu throughout the process, but product/biomass yield (Y(p/x)) was influenced by mu at the pre-induction stage. By applying an efficient feeding strategy, in which the mu was maintained at the maximum attainable level, recombinant protein was accumulated up to a level of 60% of the total cell protein and its productivity was increased significantly. In this case, the overall productivities of biomass and recombinant protein were 6.36 g l(-1) h(-1) and 2.1 g l(-1) h(-1) respectively, in comparison with 1.91 g l(-1) h(-1) and 0.16 g l(-1) h(-1) during exponential feeding, in which the specific growth rate was kept constant throughout the entire process.

To reduce the degradation pathway of rhIFN-gamma (recombinant human interferon-gamma), the susceptibility against oxidative stress during fermentation in Escherichia coli cells and in purification process were investigated. Fermentations of recombinant E. coli were performed at 5, 30 and 60% DO (dissolved oxygen) concentrations. The expressed rhIFN-gamma is purified in three-step chromatography processes with 99.9% purity under reducing and non-reducing conditions. Recombinant IFN-gamma production, carbonyl and dimeric contents and antiviral-specific activity of purified protein were monitored. The increase in carbonyl content was taken to be an indicator of protein oxidation. DO concentration did not show any noticeable effect on rhIFN-gamma production. During fermentation, the carbonyl-group content showed no significant increase at 5 and 30% DO but a 10-fold increase at 60% DO concentration was observed. The antiviral-specific activity of purified rhIFN-gamma was decreased 35 and 69% at 30 and 60% DO concentrations respectively. After the purification process, under non-reducing conditions, the activity of purified protein decreased to 30% of its original value. The degree of dimeric forms of protein was found to depend on the O2 concentration during fermentation and purification.