Preparative purification of B-phycoerythrin from the microalga Porphyridium cruentum by expanded-bed adsorption chromatography.

B-Phycoerythrin (B-PE) is a major light-harvesting pigment of microalgae. Due to its high fluorescence efficiency and its intense and unique pink color, it is widely used as a fluorescent probe and analytical reagent as well as being employed as a natural dye in foods and cosmetics. Tedious methodologies for B-PE purification have been published. In this work we present a new, fast, preparative and scaleable two-step chromatographic method for B-PE purification from the red microalga Porphyridium cruentum. Initially, phycobiliproteins were released from the microalga cells by osmotic shock and captured by applying the centrifuged cell suspension to a column containing 74 ml Streamline-DEAE equilibrated with 50 mM acetic acid-sodium acetate buffer, pH 5.5, using expanded-bed adsorption chromatography at an upward flow of 200 cm h(-1). After adsorption, washing was carried out in the expanded-bed mode. Having removed unbound proteins and cellular debris, the bed was allowed to sediment and a B-PE-rich solution was eluted with a downward flow of the same 250 mM buffer. In order to obtain pure B-PE, we utilized conventional ion-exchange chromatography with a column of DEAE-cellulose loaded directly with the eluate from Streamline-DEAE and developed using a discontinuous gradient of acetic acid-sodium acetate buffer, pH 5.5. With this new methodology, 66% of B-PE contained in the biomass of the microalgae was recovered, a value significantly higher than those obtained following other methodologies. The B-PE purity was tested using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and spectroscopic characterization.

Cytomegalovirus and paediatric renal transplants: is this a current issue?

OBJECTIVE: An observational retrospective multicentre study of kidney transplants in paediatric patients was performed to evaluate the current situation of cytomegalovirus (CMV) in this population, before our participation in an international clinical trial of prophylaxis for 6 months. MATERIAL AND METHOD: Our study included 239 patients aged <19 years, from 5 Spanish centres between 2005-2009, with 1 year of follow-up. RESULTS: Pretransplant CMV serology was negative in 54% of recipients and 34.7% of donors. Sixty patients (25.1%) were considered at high risk (D+/R-) for CMV infection. Prophylaxis was used in 80.8% of recipients, including all high-risk patients, for an average time of 65.5 days. CMV viraemia occurred in 24.26% (58 cases among 239 patients), and disease in 6.7%. CMV infection was associated with serological status (D/R) (P<.001), positive serology of the donor (P<.001) and duration of prophylaxis <20 days (P<.05). There were no cases of patient or graft loss secondary to infection, nor resistance to treatment. CONCLUSIONS: The main preventative strategy against CMV in paediatric renal transplantation in our country is chemical prophylaxis (81%), with an incidence of infection and disease of 24% and 6.7%, respectively. There were no serious direct or indirect effects in the first year post-transplant. The incidence is mainly linked with serological D/R and positive donor status.