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Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 1,117 records · Page 62Linked to original sources
PubMed1996

Pharmacokinetics and efficacy of low-dose all-trans retinoic acid in the treatment of acute promyelocytic leukemia.

A clinical trial was conducted in order to evaluate the therapeutic effect and side-effects of low-dose ATRA in the treatment of acute promyelocytic leukemia (APL). We compared the pharmacokinetic features in normal individuals with single oral ATRA at 15 mg/m2 and 45 mg/m2, respectively. The results showed that maximal plasma concentration (Cpmax) with oral 15 mg/m2 ATRA was high enough (10(-6) M) to induce APL cell differentiation. Based on these results, 27 cases of de novo APL patients were treated with continuous oral ATRA at the dose of 15-20 mg/m2/day and 24/26 evaluable cases (92%) achieved clinical CR after 13 to 67 days of ATRA treatment. No patient experienced RAS and DIC. The Cpmax with a single dose of ATRA on day 1 of treatment and immediately at CR obtained with continuous ATRA in three cases demonstrated similar values in one patient and an approximately two-fold decrease in two patients. More importantly, compared with a relatively well-matched historic group of 20 APL patients treated with high-dose ATRA, our results suggest that low-dose ATRA is as effective as high-dose in treating APL patients and may provide advantages through decreased hyperleukocytosis and other side-effects.

Administration, Oral↗
PubMed1996

[Transgenic Brassica napus resistant to turnip mosaic virus].

A system for obtaining regenerated plantlets of "double low" Brassica napus by using cotyledonary petioles as material was established. The turnip mosaic virus coat protein (TuMV-CP) gene inserted in the binary vector pBTu in the Agrobacterium tumefaciens LBA 4404 was integrated into Brassica napus through co-culture of cotyledonary petioles with LBA4404, and the material in co-culture was selected under the stress of Kanamycin. Regenerated plantlets were obtained, and the specific TuMV-CP gene was proved to be integrated into the genomic DNA of the regenerated plants by the specific PCR amplification, dot hybridization and Southern blot. All these transgenic plants were proved to be resistant to virulent TuMV by virus challenge in different degree.

Brassica↗
PubMed1996

Roles of dopamine receptors in long-term depression: enhancement via D1 receptors and inhibition via D2 receptors.

The effects of both the activation and the blockade of D1 or D2 dopamine receptors on long-term depression (LTD) of synaptic transmission, and the involvement of NMDA and GABA receptors in LTD, were investigated in CA1 neurons of rat hippocampal slices. Low-frequency stimulation (LFS, 450 pulses at 1 Hz) produced LTD of the slope of field EPSPs (-14.3%, mean, n = 10). The induction of LTD was blocked by the NMDA receptor antagonist, AP5 (1.4%, n = 7), by the D1 receptor antagonist, SCH-23390 (3.5%, n = 8), or by the D2 receptor agonist, LY-171555 (4.4%, n = 8). Either the activation of D1 receptors by SKF-38393 or the blockade of D2 receptors by sulpiride produced significantly larger LTD than the control LTD (-31.1%, n = 11; -30.6%, n = 9, respectively). Although LTD was blocked by picrotoxin, a GABAA receptor/Cl- channel antagonist (4.9%, n = 8), LTD was produced by LFS in the medium containing both SKF-38393 and picrotoxin (-27.3%, n = 7). These results indicate that: (1) the induction of LTD by LFS in hippocampal CA1 neurons is under the influence of both NMDA and GABA receptors; (2) both D1 and D2 receptors are involved in the modulation of LTD in that the activation of D1 receptors enhances LTD, while that of D2 receptors inhibits LTD, and (3) while the induction of LTD is blocked by picrotoxin, this effect is superseded by SKF-38393.

2-Amino-5-phosphonovalerate↗
PubMed1996

Morphological observations of vas deferens occlusion by the percutaneous injection of medical polyurethane.

Histological observations of 20 occluded vas segments obstructed by the standard procedure of medical polyurethane-vas occlusion in 10 volunteers requesting vasectomy and of 20 vas segments with plugs removed from 10 vas-occluded men requesting vas reversal were carried out in order to elucidate the mechanism of vas occlusion by medical polyurethane (MPU). Twenty vas deferens in vasectomy group were ruptured, only a small amount of MPU elastomer remained within the vas lumen, most having leaked through to encircle the ruptured vas. Histomorphology of the removed vas segments from 10 vas-occluded men, who had undergone MPU-vas occlusion 4 years earlier, showed diffuse proliferation of connective tissue, fibrosis, or hyalinization of fibroplastic tissue and local infiltration of lymphocytes and macrophages. The vas lumen both proximal and distal to the plugs was completely blocked. Sperm granuloma, foreign body granuloma, proliferation of nerve fibers and local infiltration of lymphocytes were found in four vas-occluded men with painful nodules. These results suggest that the contraceptive mechanism of MPU-vas occlusion could be the result of secondary obstruction due to tissue proliferation by MPU irritation after the rupture of the vas deferens.

China↗
PubMed1996

Allergenic and antigenic determinants of latex allergen Hev b 1: peptide mapping of epitopes recognized by human, murine and rabbit antibodies.

BACKGROUND: The rubber elongation factor in Hevea rubber (Hev b 1) is one of the most important latex allergen and is leading cause of latex type 1 hypersensitivity in children with spina bifida. OBJECTIVE: The aim of this study was to define the allergenic and antigenic epitopes of Hev b 1. METHODS: The immunoglobulin- (Ig)E and IgG antibody binding sites on Hev b 1 allergen were delineated by enzyme linked immunosorbent assay (ELISA) using synthetic overlapping peptides covering the whole Hev b 1 sequence. In order to improve the binding capacity and specificity all peptides were biotinylated at the N-terminal end via a 6-aminohexanoic acid as spacer and then adsorbed to streptavidin pre-coated microtitre plates. Fine mapping to define the essential amino acid residues for the antibody binding was achieved by using overlapping peptides with one amino acid offset. RESULTS: It was demonstrated that the IgE epitopes were located in different regions of Hev b 1 including the C-terminal segment (121-137) and the segments with amino acid residues of 30-49 and 46-64. Two monoclonal antibodies (MoAbs) II2F3 and II4G9 raised against purified Hev b 1 recognized the C-terminal segment only. The results of epitope mapping with three rabbit antisera revealed that five positive peptides, including the epitope peptides 31-49, 46-64 and 121-137, were involved in the antibody-binding sites. Fine mapping on the segments 46-64 and 121-137 showed that the two MoAbs reacted with the peptide 125-134 in the C-terminal region, whereas the peptide with amino acids 124-134 was essential for recognition by human IgE antibodies. Epitopes to rabbit polyclonal IgG and human IgE were also found to be involved in the amino acid residues of 47-59. CONCLUSION: Our results indicate that the most allergenic/antigenic portions of Hev b 1 allergen are the C-terminal region and the region with amino acid residues of 31-64. In both regions, the minimal IgE-binding epitope is almost identical with the IgG-binding epitope.

Allergens↗
PubMed1996

[Anti-herpes simplex virus action of combined therapy with cyclocytidine and ganciclovir].

OBJECTIVE: The study was designed to investigate the combined effect of cyclocytidine (CC) and ganciclovir (GCV) on herpes simplex virus-1 (HSV-1) in cell culture. METHODS: The 50% inhibition concentrations of HSV-1 plaque formation (IC50) of CC, GCV alone and in combination were determined by the inhibitory test of plaque formation. The combined anti-HSV-1 effect of CC and GCV was evaluated by a graphic method and fractional inhibitory concentration (FIC) indexes. RESULTS: IC50 of CC and GCV was 0.19 and 0.1 micrograms/ml, respectively. The combination of CC with GCV produced significantly synergistic activity against HSV-1 in cell culture. FIC indexes were all below 0.75. The combined therapy of CC and GCV can also decrease and delay the emergence of drug-resistant variants. CONCLUSION: These results suggest that this combined therapy of CC and GCV may be a potentially effective means in the management of patients with HSV-1 ocular infection.

Ancitabine↗
PubMed1996

[Anti-tumor effects of bispecific monoclonal antibody targeted human monocytes-macrophages on hepatoma cells].

OBJECTIVE: To study anti-tumor affects of bispecific monoclonal antibody targeted human monocytes-macrophages on hepatoma cells. METHODS: The fragment of monoclonal antibody HAb18F(ab')2 which has high affinity to hepatoma cells and the fragment of monoclonal antibody antimonocytes/macrophages MAb7F(ab')2 were cross-linked with N-succinimidyl 3-(2-pyridl-dithil) propionate. RESULTS: Heteroaggregated monoclonal antibodies HAb18F(ab')2-MAb7F(ab')2 could bind to hepatoma cells as well as monocytes-macrophages. They were purified with FPLC Sephacryl S-200. The bispecific character was identified with Indirect Immunofluorescent Staining. CONCLUSION: In vitro cytotoxicity assay showed that HAb18F(ab')2-MAb7F(ab')2 could significantly enhance the lysis of human hepatoma cells by human monocytes-macrophages.

Adenoma↗
PubMed1996

[Enhancing immunogenicity of pres antigen of hepatitis B virus by fusing genetically it with interleukin-2].

OBJECTIVE: To combine the bioactivities of human interleukin-2 (IL-2) with entire preS antigen of hepatitis B virus (HBV), and search for specific immunotherapeutic agent against chronic hepatitis B. METHODS: A chimeric gene composed of preS gene from HBV DNA and human IL-2 cDNA was constructed by using polymerase chain reaction and genetic engineering methods, and a novel type of chimeric protein (IL-2-preS) was expressed with high efficiency in E. coli transformed by the chimeric gene clone. RESULTS: It was confirmed that the chimeric protein retained the full bioactivities of natural IL-2 and preS molecules, such as maintaining CTLL cells to proliferate, with the specific activity being about 10(7)u/mg protein, and binding with monoclonal antibodies against preS1 and preS2 and polymerized human serum albumin (PHSA), etc. It was shown that the titer of antibody against preS antigen in mice induced by IL-2-preS was 9, 11 and 13 times more than those induced by a mixture of IL-2 with preS antigen, MS-2-preS chimeric protein and preS antigen alone, respectively. CONCLUSION: IL-2-preS potentiates immunogenecity of preS antigen and enhances immune responses of human bodies against preS antigen. In addition, IL-2-preS is of double targetting effect in human bodies, and may be used as a new generation of immunotherapeutic agent for chronic hepatitis B and hepatocellular carcinoma.

Animals↗
PubMed1996

[One-stage repair of hypospadias with double-pedicle scrotum septal flap].

Nine cases of hypospadias were repaired using double-pedicle scrotum septal flap from December 1991 to December 1992. Success was achieved in all cases. The key point of success was to preserve the vascular pedicle to the flap. The operative technique and the management of complications are described.

Child↗
PubMed1996

[Study of the relationship between complement activation and vascular endothelial damage in pregnancy induced hypertension].

OBJECTIVE: To evaluate the relationship between complement activation and vascular endothelial damage in pregnancy induced hypertension (PIH). METHODS: We quantified C1q, B-factor (BF) and C1-inhibitor (C1-INH) in peripheral and retroplacental sera of 35 nulliparous PIH patients and 20 normotensive controls with double antibody sandwich ELISA. Circulating endothelial cell (CEC)of the two groups were isolated with the density gradient system of Percoll liquid and counted under microscope. The correlation between CEC and C1q was analysed. RESULTS: (1) C1q concentrations in peripheral and retroplacental sera were significantly decreased in PIH patients than that in normotensive controls, however, the concentrations of BF and C1-INH were significantly elevated in PIH patients. The changes in retroplacental serum were much more profound than those in peripheral serum. (2) The count of CEC was significantly increased in PIH patients than that in controls. (3) The count of CEC was negatively correlated to C1q concentration. CONCLUSIONS: Not only the classical complement activation pathway but also the alternative complement activation pathway and complement regulatory protein play important roles in the pathogenesis of PIH, and complement activation and vascular endothelial damage is correlated. Evaluation of C1q, BF, C1-INH and CEC may be of value in clinical monitoring and management of PIH.

Cell Count↗
PubMed1996

[In vitro transformation of human embryonic nasopharyngeal epithelial cells with Epstein-Barr virus].

UNLABELLED: EBV from B95-8 cells were used to infect directly the human embryonic nasopharyngeal epithelial (HENE) cells in vitro. RESULTS: Primary HENE cells treated with EBV did not have a significantly increased colony-forming rate in soft agarose, while cells that were treated with EBV in combination with tumor promotor 12-O-tetradecanoylphorbol-13 acetate (TPA) showed a marked increase in colonyforming rate from 0-5 cells to 20-40 colonies per 10,000 cells. (2) HENE cells treated with inactivated (56 degrees C for 30 minutes) virus, in spite of adding TPA at the same time, did not significantly increase agarose colony forming rate; (3) HENE cells treated with TPA after EBV exposure for a week had significantly increased colony forming rate in soft agarose, while the cells exposed to EBV after using TPA treatment did not. In addition, EBV BNLF1 (LMP) fragment in HENE cells treated with EBV or EBV+TPA was detected by polymerase chain reaction using specific oligonucleotide primer. Only HENE cells treated with EBV+TPA presented positive band in aragose gel electrophoresis. The results suggest that transformation of EBV on HENE cells depends on infectious virus and an intact viral genome. TPA not only can promote the transformation, but also promote EBV's entering HENE cells.

Base Sequence↗
PubMed1996

Molecular diagnosis of hemophilia A in Chinese patients by an analysis of inversions in the factor VIII gene.

Hemophilia A is an X-linked bleeding disorder caused by deleterious mutations in the factor VIII gene. An inversion caused by introchromosomal homologous recombination between the A gene located in intron 22 of the factor VIII gene and one of the two telomeric A genes has been recently described as the common cause of about 50% of cases of severe hemophilia A. The rearrangement can be readily detected by a Southern blotting procedure. We report use of this procedure to detect rearrangements in 106 unrelated Chinese hemophilia A cases. In 49.3% of the patients with severe disease an inversion was found, but no inversion was detected in any of the patients with moderate or mild disease. The majority of inversions (91.4%) involved the most distal A gene; in a minority (8.6%) the more proximal A gene was involved. These results indicate that intron 22 inversion is the most important molecular defect causing Chinese hemophilia A and that analysis for intron 22 inversion may be the first-line test in the molecular diagnosis of severe hemophilia A.

Asian People↗
PubMed1996

Addition of purified prostate specific antigen to serum from female subjects: studies on the relative inhibition by alpha 2-macroglobulin and alpha 1-antichymotrypsin.

PURPOSE: Two forms of prostate specific antigen (PSA), 1 complexed to alpha 1-antichymotrypsin and the other a free PSA, are recognized by current commercially available immunoassays. A third form of PSA complexed to alpha 2-macroglobulin also is present in the serum. To study these 3 different molecular forms of PSA in vivo, we simulated leakage of PSA from the prostate into the serum in vitro. MATERIALS AND METHODS: Purified seminal fluid PSA was incubated with fresh sera from female subjects at different concentrations. Following gel filtration chromatography, the 3 forms of PSA were studied by immunoassays and Western blot analysis. RESULTS: Using a commercial immunoassay, 60% of immunoreactivity of seminal fluid PSA was lost after incubation with sera from female subjects. Western blot analysis showed that most of this loss in PSA signal was caused by complexation to alpha 2-macroglobulin. Minimal, if any, complexation to alpha 1-antichymotrypsin occurred even when excess alpha 1-antichymotrypsin was added to the serum. CONCLUSIONS: Our studies demonstrated that alpha 2-macroglobulin is a much stronger inhibitor to PSA than alpha 1-antichymotrypsin. Further studies of these complexes may be important. They clearly explain why spiking PSA into sera from female subjects to be used as quality controls for PSA assays leads only to the free form of enzymatically inactive PSA in the serum, and not to the dominant form of complexed PSA and alpha 1-antichymotrypsin present in human serum.

Female↗