Biomedical subjects

P Qiu

Publications and source records attributed to P Qiu.

22 records · Page 2Linked to original sources

PubMed1995

Yeast-prepro-alpha-factor-leader-region-directed synthesis and secretion of truncated human macrophage colony-stimulating factor in the silkworm Bombyx mori.

Human macrophage colony-stimulating factor (hM-CSF) cDNA joined to the leader region of the precursor of the yeast mating pheromone alpha-factor (MF alpha L) was expressed at high levels in BmN cells and in silkworm (Bombyx mori) larvae, using recombinant Bombyx mori nuclear polyhedrosis virus, as a vector. The biological activity of rhM-CSF detected in the haemolymph was 1 x 10(6) colony-formation units/ml, approximately half of the expression level directed by the native signal peptide of hM-CSF in silkworm larvae. The secreted rhM-CSF was purified to homogeneity. N-terminal analysis showed that the signal peptide had been removed, indicating that insect cells possess the enzymic activity necessary to cleave the pro-alpha-factor leader region from the fusion protein at the carboxy side of Lys-Arg dibasic residues, which is the cleavage site recognized by KEX2 endopeptidase in yeast cells.

Amino Acid Sequence↗

PubMed1994

Establishment of an adherent cell feeder layer from human umbilical cord blood for support of long-term hematopoietic progenitor cell growth.

Previous attempts to establish a stromal cell feeder layer from human umbilical cord blood (HUCB) have met with very limited success. It has been suggested that there is an insufficient number of stromal precursor cells in HUCB to form a hematopoietic-supporting feeder layer in primary cultures. The present study shows that HUCB does contain a significant accessory cell population that routinely develops into a confluent, adherent cell layer under defined primary culture conditions. HUCB-derived adherent layers were shown to support long-term hematopoietic activity for an average of 4 months. This was achieved by using a customized coverslip with a modified surface structure as the cell attachment substratum and using a specialized culture feeding regime. We have characterized the various cell types (including fibroblasts, macrophages, and endothelial cells) and extracellular matrix proteins (including fibronectin, collagen III, and laminin) that were present in abundance in the HUCB-derived adherent cell layer. In contrast, oil red O-staining fat cells were rarely detected. ELISA and bioassays showed that stem cell factor and interleukin 6 were produced by the HUCB stromal cell cultures, but interleukin 3 or granulocyte/macrophage colony-stimulating factor was not detected. Application of this hematopoietic culture system to transgenic and gene therapy studies of stem cells is discussed.

Antigens, CD↗

PubMed1994

Expression of biologically active monomeric form of human M-CSF in baculovirus infected silkworm, Bombyx mori.

The human macrophage colony stimulating factor (hM-CSF) in its monomeric form has been over-produced in BmN cells and in silkworm larvae infected with the recombinant baculovirus Bm284M-CSF. The recombinant monomeric M-CSF (rhM-CSF) exhibited the activity of 8-14 x 10(4) units/ml of cell culture medium. When the insect larvae were infected with the recombinant virus, the maximum rhM-CSF was expressed 4-5 days post infection with an activity of 3 x 10(6) units/ml hemolymph. The monomeric rhM-CSF was purified to homogeneity through three steps of purification. A pilot purification yielded 1 mg of homogeneous monomeric rhM-CSF from 10 larvae. The purified rhM-CSF monomers gradually dimerized in vitro. In contrast, the crude or the semi-purified monomers did not dimerize in vitro, indicating that the presence of an unknown moiety in the rhM-CSF preparations obtained from hemolymph interfered with dimerization.

Alkylation↗

PubMed1993

[Protective effects of tetrandrine on calcium paradox in isolated rat heart].

The protective effects of tetrandrine (Tet) on calcium paradox in isolated Langendorff's heart in rats were investigated. Tet was shown to reduce the release of lactate dehydrogenase (LDH) and protein from myocardial tissues and the loss of K+, Mg2+ and accumulation of Ca2+, Na+ in myocardial tissues during calcium paradox in a concentration-dependent manner. Decrease of Fe and Zn and increase of Cu in myocardial tissues were observed in calcium paradox and Tet 27 mumol/L was found to inhibit the decrease of Fe and Zn. In addition, Tet was also found to inhibit the decrease of Ca2+ and the increase of Na+ in myocardial tissues during calcium-free perfusion. These results indicate that Tet can protect the myocardium against calcium paradox by stabilizing cellular membrane and inhibiting the influx of Ca2+.

Alkaloids↗