The probability of microbiological contamination during the collection and processing of umbilical cord blood / 中国实验血液学杂志

To study the pathogens incidences in cord blood and the efficiency of different detective methods, 60 samples were drawn and reserved from collected and processed cord blood, respectively. The BACTEC 9050 system, improved Martin/thioglycollate broth (22 degrees C) and thioglycollate broth (35 degrees C) were employed to detected bacteria (including fungus) at the same time. Two hundred and six cord blood serum samples were used to detect the HBV DNA and HCV RNA by molecular biology technique, HBsAg, Anti-HBC, Anti-HCV, Anti-HCMV-IgM, HTLV-1, HTLV-2, HIV-1 and HIV-2 by ELISA and RBC agglutination test were used to detect the TPHA. Results showed that using BACTEC 9050 system, the incidence of bacteria and fungus was 3.33% and 0% respectively in collected cord blood; in processed cord blood, the rates increased to 6.67% and 1.67%, respectively. The sensitivity of BACTEC 9050 was higher than that of Martin/thioglycollate broth (22 degrees C/35 degrees C) culture. In 206 serum samples, the positive rate of HBV DNA was 5.8%, HCV RNA was 2.4%, HBsAg was 2.4%, HCMV-IgM was 1.89%, HCV was 2.4% and Anti-HBC was 29.4%. In those samples that Anti-HBC was positive, the positive rate of HBV DNA was 6.7%. It was concluded that the incidences of microbiological contamination in cord blood were high. The routine culture system would lead to false negative results of obligate anaerobes. It was necessary to replace the current culture system with improved system, such as BACTEC 9050 system. The molecular biology technique would make up for the default of ELISA.

Effects of cryopreservation length on the proliferative potential of cord blood hematopoietic cells in vitro / 中国应用生理学杂志

<p><b>AIM</b>To study the effects of cryopreservation length on the proliferative potential of hematopoietic cells derived from cord blood.</p><p><b>METHODS</b>Using Dextran-40 and 10% DMSO as cryoprotectants, separated nuclear cells were stored in liquid nitrogen after they were freezed according programme. One month or 4 months later, they were thawed and expanded in serum-free medium for culture and expansion of hematopoietic cell (SFEM) for 5 weeks. Dynamic results were detected every week.</p><p><b>RESULTS</b>At the 5th week of expanding, TNC were expanded for 1499.0 +/- 115.6-folds and 1513.0 +/- 110.4-folds, respectively. CD34+ cells and CFCs reached to their highest level at the 2nd week and at the 3rd week. CD34+ cells were expanded for 63.8 +/- 6.1-folds and 62.4 +/- 5.7-folds, respectively. CFCs were expanded for 53.8 +/- 6.3-folds and 54.8 +/- 6.7-folds, respectively. Between the two kinds of cells, statistical significant difference in proliferative potential wasn't detected.</p><p><b>CONCLUSION</b>In ideal cryopreservative condition, the cryopreservation length would do not affect the proliferative potential of cord blood hematopoietic cells.</p>

The Prediction of the Molecular Biology Characteristics of Recombinant Fusion Exotoxin B7-1-Linker-PE40 and B7-2-Linker-PE40 / 中国实验血液学杂志

In order to confirm the reasonability of designed recombinant exotoxin B7-1-Linker-PE40 and B7-2-Linker-PE40, their molecular biology characteristics, such as flexibility, antigenicity, hydrophilicity, epitope and secondary structure, were predicted by using a computer software GOLDKEY. It had been found that the recombinant fusion exotoxin had kept the epitope characterstics of B7-1, B7-2 and PE40, and had not got new epitope, and the antigenicity in flexible linker was extxemely low. The linker inserted in the recombinant fusion exotoxin had low epitope, low antigenicity and high flexibility. Compared to B7-1, B7-2 and PE40, there are several amino acid residues changes in B7-1-Linker-PE40 and B7-2-Linker-PE40, respectively, which might have some effect on secondary structure of the recombinant fusion exotoxins. Western blot analysis revealed that both B7-1-Linker-PE40 and B7-2-Linker-PE40 could bind specifically with antibodies against B7-1, B7-2 and PE40, respectively. The result of Western blot was consistant with the computer prediction that the recombinant proteins retain the antigenicity and spacial structure of B7 and PE40. It is suggested that both fusion proteins designed and constructed were resonable and computer analysis would be helpful for us to study the biological activity of the recombinant fusion exotoxin B7-1-Linker-PE40 and B7-2-Linker-PE40 and construct other recombinant proteins further.