Detection of SARS-CoV RNA in stool samples of SARS patients by nest RT-PCR and its clinical value / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate of severe acute respiratory syndrome (SARS) convalescent stool shedding by RT-PCR.</p><p><b>METHODS</b>One hundred and three stool samples from 46 SARS patients were collected on May 16th, 20th, and 23rd, 2003. For each sample, RNA was extracted using commercial kit and 7 Nest RT-PCR using a 14-pair different SARS-associated coronavirus (SARS-CoV) special primers were carried out simultaneously.</p><p><b>RESULTS</b>Among these 46 SARS patients, 17 cases (37.0%) were stool SARS-CoV RT-PCR negative, and 29 cases (63.0%) were SARS-CoV RT-PCR positive. The duration of positive cases lasted (31.76 +/- 10.78) d (12-64 d). The longest stool shedding case in this study lasted 64 days. Two serial stool samples and for each sample 2 RT-PCR tests using different primers were positive in this case.</p><p><b>CONCLUSIONS</b>Our study observed longest stool shedding of SARS patients to be 64 days after initial onset of SARS. The average stool shedding was 32 days. Hence it is important to think highly of SARS convalescent patient stool sterilization.</p>

Cultivation of human mesenchymal stem cells on macroporous CultiSpher G microcarriers / 中国实验血液学杂志

Adult human bone marrow-derived mesenchymal stem cells (MSCs) were cultured on microcarriers in spinner flasks and were compared with those in conventional culture in 12-well plates. For the production of adherently growing MSCs, macroporous CultiSpher G gelatin microcarriers were used in concentration of 1 g/L. The cells were seeded in a density of 5 x 10(4) cells/ml in both spinner culture and conventional stationary culture. The result showed that after 7 days of cultivation a maximum viable cell concentration of 5.15 x 10(5) cells/ml was obtained in spinner culture. Whereas the cell density increased to a maximum of 1.675 x 10(5) cells/ml on day 5 in conventional stationary culture. Lactate was produced up to 12.06 mmol/L in spinner culture and up to 13.10 mmol/L in stationary culture, and glucose was consumed up to 7.38 mmol/L and 5.37 mmol/L respectively. The average lactate yield on glucose consumption in spinner culture was only 1.63, lower than that in stationary culture 2.44. This indicated that the energy metabolism in spinner culture was significantly more efficient than that in conventional culture. After spinner culture for 12 days, the MSCs maintain the characteristics of stem cells. It is concluded that the microcarrier culture system is a suitable way to expand the seeding cells for tissue engineering.

Single-chain urokinase-type plasminogen activator (scu-PA) purification by immuno-affinity chromatography / 生物工程学报

The only difference of primary structure between single-chain prourokinase (pro-UK or scu-PA) and two-chain urokinase (UK or tcu-PA) is the cleavage of a single peptide bond (Lys158-Ile159) and transform scu-PA into its active two-chain form. A 13-peptide (Thr-Leu-Arg-Pro-Arg-Phe-Lys-Ile-Ile-Gly-Gly-Glu-Cys), which spans the cleavage peptide bond, was synthesized and linked to KLH (Keyhole limpet hemocyanin). The Balb/c mice were immunized by the conjugated protein with proper adjuvant. According to the Kohler and Milstein's methods, a hybridoma cell line G7 secreting monoclonal antibody specific for scu-PA was obtained. The anti-scu-PA McAb, purified from the supernatant of porous microcarrier hybridoma cell culture, was conjugated to CNBr-activated Sepharose 4B to prepare an immuno-affinity chromatography column. The u-PA was purified only by this affinity column from the supernatant of cultivating the u-PA-producing recombinant CHO cell, the u-PA recovery ratio is 90.4%, the purification factor was about 50, with the specific activity of 1.2 x 10(5) IU/mg, the scu-PA ratio in the u-PA product was 96.3%. Compared to immuno-affinity chromatography, the 3-step process for purifying u-PA (cation-exchange column, gel filtration column and benzamidine affinity column) has a u-PA recovery ratio of about 65%, with a specific activity of 1.0 x 10(5) IU/mg, and an scu-PA ratio of about 90%. These results showed that immuno-affinity chromatography is simple to recover u-PA and effective to separate scu-PA from tcu-PA.