Self cycling fermentation (SCF) in a stirred tank

Self cycling fermentations (SCF's) were conducted in an apparatus based on a commercial model two litre stirred tank fermenter. An automated control system and peripheral vessels were used to perform cycling control, medium addition, broth removal and sampling.The apparatus was used to grow Bacillus subtilis and Acinetobacter calcoaceticus on different media. Both organisms supported a steady state SCF. Measurements of biomass, cycle time and minimum dissolved oxygen all gave repeatable results. Results were comparable to literature values for a cyclone column SCF apparatus.A gas analyzer was installed to measure oxygen and carbon dioxide concentrations in the effluent gas. The response of the gas analyzer paralleled that of the dissolved oxygen measurements

Preparation and evaluation of 89Zr-Zevalin for monitoring of 90Y-Zevalin biodistribution with positron emission tomography

Purpose: To evaluate whether 89Zr can be used as a PET surrogate label for quantification of 90Y-ibritumomab tiuxetan ( 90Y-Zevalin) biodistribution and dosimetry before myeloablative radioimmunotherapy. Methods: Zevalin was labelled with 89Zr by introducing N-succinyldesferal (N-sucDf) as a second chelate. For comparison of the in vitro stability of 89Zr-Zevalin and 88Y-Zevalin (as a substitute for 90Y), samples were incubated in human serum at 37°C up to 6 days. Biodistribution of 89Zr-Zevalin and 88Y-Zevalin was assessed at 24, 48, 72 and 144 h p.i. by co-injection in nude mice bearing the non-Hodgkin's lymphoma (NHL) xenograft line Ramos. The clinical performance of 89Zr-Zevalin-PET was evaluated via a pilot imaging study in a patient with NHL, who had undergone [18F]FDG-PET 2 weeks previously. Results: Modification of Zevalin with N-sucDf resulted in an N-sucDf-to-antibody molar ratio of 0.83±0.04. After radiolabelling and purification, the radiochemical purity and immunoreactivity of 89Zr-Zevalin always exceeded 95% and 80%, respectively. 89Zr-Zevalin showed the same stability in serum as 88Y-Zevalin, with a radiochemical purity >95% during a period of 6 days. The co-injected 89Zr-Zevalin and 88Y-Zevalin conjugates showed a very similar biodistribution, except for liver and bone accumulation at 72 and 144 h p.i., which was significantly higher for 89Zr than for 88Y. PET images obtained after injection of 89Zr-Zevalin showed clear targeting of all known tumour lesions. Conclusion: 89Zr-Zevalin and 88Y-Zevalin showed a very similar biodistribution in mice, implying that 89Zr-Zevalin-PET might be well suited for prediction of 90Y-Zevalin biodistribution in a myeloablative setting