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Biomedical subjects

Juan Li

Publications and source records attributed to Juan Li.

At least 127 records · Page 7Linked to original sources
PubMed2004

[Expression of CD117 antigen on multiple myeloma and its significance].

BACKGROUND & OBJECTIVE: Leukocyte differentiation antigen CD117 is one of the targets that tyrosine kinase selective inhibitors work on. Whether CD117 is expressed on the cell surface, and the expression level are highly correlated with tyrosine kinase selective inhibitors. This study was designed to investigate the expression of CD117 on multiple myeloma (MM) cells, which may provide a theoretical evidence for the use of tyrosine kinase selective inhibitors in MM,meanwhile,the importance of CD117 expression on MM cells was estimated. METHODS: CD117, CD56, and CD54 were measured by three-color flow cytometry with CD45/SSC gating strategy. RESULTS: Of 48 patients with MM, 17 (35.5%) had positive CD117 expression on myeloma cells, 39 (81.2%) had positive CD56 expression, and 48 (100.0%) had positive CD54 expression. CD117 expression on myeloma cells was lower than CD56, and CD54. CD117 positive expression was positive correlated with the percentage of myeloma cells in bone marrow. CD117 positive in IgG type of MM was 64%, higher than other types such as light chain or IgA. CD117 positivity showed no significant difference in different stages (P >0.05), and in patients haven't been pretreated, or relapsed after pretreated (P >0.01). In MM patients haven't been pretreated, the reaction rate of VAD chemotherapy in CD117 positive cases was 71.4%, and showed no significant difference (P >0.05) compared with the reaction rate of 66.7% in CD117 negative cases. CONCLUSION: CD117 can be regard as the related tumor antigen of MM, and may be a valuable marker in the use of tyrosine kinase selective inhibitors, which inhibit the signal conduct to the target.

Adult↗
PubMed2004

[Response rate of AML-XH-99 protocol in the treatment of 82 childhood acute myeloid leukemia].

OBJECTIVE: To evaluate the outcomes of childhood acute myeloid leukemia (AML) treated with AML-XH-99 protocol and explore how to improve the event-free survival (EFS) rate. METHODS: Eighty-two patients entered AML-XH-99 clinical trial. Survival rates were evaluated by Kaplan-Meier method with SPSS. RESULTS: Among the 82 patients, 58 (70.7%) achieved complete remission (CR) after one course treatment, and the total CR rate was 84.1%. The overall 5 year EFS rate was (46.1 +/- 9.1)% and disease-free survival (DFS) rate was (54.3 +/- 10.3)% over a median observation period of 23 months. The 5 year EFS rate of 56 patients received high-dose cytarabine(HD-Ara-C) as intensification therapy was (47.2 +/- 12.9)%. Relapse occurred in 19 patients (26.0%) with a median time of 10 months (ranges 2 approximately 53 months), 28 patients died. CONCLUSION: AML-XH-99 protocol resulted in a higher CR rate, especially one course CR rate, which was one of the key factors for long-term EFS and HD-Ara-C intensification therapy was effective in the treatment of childhood AML.

Adolescent↗
PubMed2004

[Study on anti-HBV effects of genetically engineered replication-defective hepatitis B virus expressing dominant negative mutants of core protein].

BACKGROUND: To explore the possibility of using HBV as a gene delivery vector, and to test the anti-HBV effects by intracellular expression of dominant negative mutants of core protein. METHODS: Two kinds of full length mutant HBV genome, which express Core-partial P and Core-S fusion protein, were transfected into HepG 2.2.15 cell lines. Positive clones were selected and mixed in respective groups with hygromycin in the culture medium. HBsAg and HBeAg, which exist in the culture medium, were tested by ELISA and intracellular HBc related HBV DNA was examined by dot blot hybridization. The existence of recombinant HBV virion in the culture medium was examined by PCR. RESULTS: The mean inhibitory rates of HBsAg were 2.74+/-3.83%, 40.08+/-2.05% (P less than 0.01) and 52.94+/-1.93% (P less than 0.01) in group 2.2.15-pMEP4, 2.2.15-CP and 2.2.15-CS, respectively. The mean inhibitory rates of HBeAg were 4.46+/-4.25%, 52.86+/-1.32% (P less than 0.01) and 41.60+/-1.65% (P less than 0.01), respectively. The inhibitory rates of HBc related HBV DNA were 15.3%, 82.0% and 67.2%, respectively. Recombinant HBV virion was detectable in the culture medium of only group 2.2.15-CP. CONCLUSION: Dominant negative mutants of core protein can efficiently suppress wt-HBV replication and the expressions of HBV antigens. With the help of wild-type HBV, the recombinant HBV genome can form and secret HBV like particles, which provides evidence that the antiviral gene will be hepatotropic expression and the antiviral effects will be amplified.

Cell Line, Tumor↗
PubMed2004

[Development of hygromycin-resistant packaging cell line for hepatitis B virus-derived vectors].

OBJECTIVE: To cooperate with the study of HBV vector, hygromycin-resistant packaging cell line was developed that allows encapsidation of plasmids into HBV particles. METHODS: Free of packaging signal, HBV genome was inserted into plasmid pMEP4, which expresses the HBV structural proteins including core, pol and preS/S proteins. HepG2 cell lines were employed to transfect with the construct. Hygromycin selection was done at a concentration of 150 micrograms/ml in the culture medium. The hygromycin-resistant clones with the best expressions of HBsAg and HBcAg were theoretically considered as packaging cell line and propagated under the same conditions. It was infected with recombinant retrovirus vector and hen selected with G418 and hygromycin in the culture medium. The existence of recombinant HBV virion in the culture medium was examined by PCR. RESULTS: Hygromycin-resistant HBV packaging cell line was generated, which harbored an HBV mutant whose packaging signal had been deleted. Expressions of HBsAg and HBcAg were detectable. Infected with recombinant retrovirus pRV-CP, the hygromycin-resistant packaging cell line was found to secrete mutant HBV particles and no wild-type HBV was detectable in the culture medium. CONCLUSION: After the packaging signal was deleted and transfected into HepG2 cell lines, the partial HBV genome lost its ability to form wild-type HBV, but conserves cis-action providing structural proteins for the packaging of the replication-defective HBV.

Cell Line↗
PubMed2004

[Replication and encapsidation of HBV mutants with the truncated C gene].

OBJECTIVE: To evaluate the replication and encapsidation of HBV mutants with the truncated C gene. METHODS: The HBV mutants with the truncated C gene were constructed by molecular cloning and PCR-based deletion in vitro. The replication and encapsidation of HBV mutants were investigated by Southern blotting, PCR and real-time fluorescence PCR respectively after transfecting the HBV mutants plasmid into HepG2 cells by using liposome. RESULTS: The C-truncated HBV mutant vectors were constructed successfully and confirmed exactly by clone sequencing and enzymes digestion. The C-truncated HBV mutants were replication defective, however, all types of HBV DNA could be detected positive in the cytoplasm and supernatant after co-transfecting the C-truncated HBV mutants plasmid and the helper constructs into HepG2 cells. The C-truncated HBV mutants were proved to produce 3-40 folds more progeny DNA than that of the wild-type HBV by DNA quantitative assay. CONCLUSION: The C-truncated HBV mutants are replication-deficient and could not replicate and encapsulate in the hepatocytes when transfected solely, however, the progeny HBV-variant viruses are encapsidated more effectively to secrete into supernatant when co-transfected with the helper construct which lacks part of 5 prime-proximal HBV RNA packaging signal Epsilon.

Cell Line, Tumor↗
PubMed2004

[A new approach to protein phosphorylation modification analysis for neuron].

OBJECTIVE: To develop a new method for analysis of protein phosphorylation modification in cultured neuron. METHODS: Cultured neurons were pre-incubated in DMEM without sodium phosphate for 15 min to deplete the metabolic pools. Neurons were then labeled with [32P] orthophosphate (2.78 x 10(6) Bq/ml) for 1.5 h and stimulated by either insulin (100 nmol/L), EGF (20 nm/L) or saline for 0, 5, 20, 60, 120 min. Reactions were terminated by freezing neurons in liquid nitrogen prior to the solubilizing of them in a lysis buffer containing 8 mol/L urea, 4% CHAPS, 2% Bio-lyte, pH 3-10, 2 mmol/L TBP. Protein concentrations were determined with Bio-Rad DC Protein Assay kit. The 32P-labled lysates isoelectrically focused on IPG Drystrip pH 3-10 or pH 4-7 Linear gels were subsequently separated in second-dimensional SDS-PAGE. The dried gel was autoradiographed for 5 days at -70 degrees C with an intensifying screen. Alternatively, the separated proteins were visualized by Coomassie Brilliant Blue (CBB) R250 straining. RESULTS: Autoradiography of the 2-DE-separated 32P-laebled neuron lysates revealed around 100 phosphoproteins. This phosphoprotein pattern was stable at 1.5 h after radiolabelling and did not vary significantly for up to 4 h further incubation in the absence of hormone. Most of the major proteins which are phosphorylated in response to insulin or EGF migrated with pH 4.6-6.5 and MW 20000-130000. Insulin and EGF induced similar but not identical patterns of protein phosphoryltion in neurons. Only a few phosphoproteins were abundant enough to be visualized by CBB straining, suggesting that abundance of these phosphoproteins is extremely low. Responses to both isulin and EGF are marked by more increased labeling of the constitutive phosphoproteins, compared with the appearance of new phosphoproteins. CONCLUSION: This approach co-application of 32P-labeled with 2-DE separation and autoradiography has proven to be specific and sensitive in phosphoprotein analysis for neuron. It was valuable in functional proteomic analysis for protein phosphorylation modification during cellular signal transduction.

Animals↗
PubMed2004

[Biological effect of serum of kidney-tonifying traditional Chinese drug-fed rats on cultured osteoblasts].

OBJECTIVE: To investigate the biological effects of the serum of rats fed with kidney-tonifying traditional Chinese drugs on cultured osteoblasts in vitro. METHODS: The culture media containing the serum from rats fed with the drugs at different doses (high, mediate and low doses) were used to treat the second passage of the osteoblasts from the skull of newborn SD rats, and the cell proliferation, differentiation and mineralization were observed. RESULTS: The serum stimulated the cell proliferation, enhanced alkaline phosphatase activity and increased the number of mineralized nodules in the cultured osteoblasts. CONCLUSION: Kidney-tonifying traditional Chinese drugs can stimulate the proliferation, differentiation and maturation of cultured osteoblasts in vitro.

Alkaline Phosphatase↗
PubMed2004

[Efficacy of imatinib mesylate, a specific inhibitor of BCR/ABL tyrosine kinase, on chronic myeloid leukemia in blast phase].

BACKGROUND & OBJECTIVE: Chronic myeloid leukemia (CML) in blast phase is refractory with a poor prognosis. This study was to evaluate efficacy of imatinib mesylate, a specific inhibitor of BCR/ABL tyrosine kinase, on CML in blast phase. METHODS: Nineteen patients with CML in blast phase (imatinib treatment group) received induction of cytarabine-based standard chemotherapy for 2 cycles, and 400 mg/d of imatinib mesylate for 4 weeks. Patients with no remission received 600 mg/d of imatinib mesylate for another 8 weeks. Treatment of 600 mg/d of imatinib mesylate was maintained if it showed effects after 8 weeks, otherwise it would be stopped. Twenty-two patients with CML in blast phase (historical control group) received inducement of cytarabine-based chemotherapy for 2 cycles, and other regimens of consolidation or continuous induction. RESULTS: Sixteen patients of imatinib treatment group achieved no hematologic remission after induction. After treated with imatinib mesylate, 6 of 16 (38%) achieved hematologic complete remission (CHR), and major cytogenetic response; 2 of 16(13%) achieved hematologic partial remission (PHR); 1 of 16 (6%) returned to chronic phase with minor cytogenetic response. Total hematologic response rate of imatinib treatment group was 57%; 1-year survival rate was 38% (6/16). Eighteen patients of historical control group achieved no hematologic remission after inducement. After treated with other regimens, 2 (11%) achieved CHR, and 1 (6%) achieved PHR. Total hematologic response rate of historical control group was 17%; 1-year survival rate was 6%(1/18), significantly lower than that of imatinib treatment group (P< 0.05). CONCLUSIONS: Imatinib mesylate may have anti-leukemic activity, and prolong survival time of patients with CML in blast phase. But problems of tumor relapse, and drug resistance are still present.

Adolescent↗
PubMed2004

[Effects of kidney-tonifying Chinese herbal drugs on human osteoblast Ca2+ intake and mineralization in vitro].

OBJECTIVE: To study the effects of kidney-tonifying Chinese herbal drugs on Ca2+ intake and mineralization of human osteoblasts in vitro. METHODS: Human osteoblasts were isolated from the iliac trabecular bone followed by purification and culture at 37 degrees Celsius with 5% CO2. The cells were identified by cell morphology, calcium nodule formation and alkaline phosphatase (ALP) activity assay. The third passage of the cultured osteoblasts were treated with 10% scrum from rat fed with the decoction of the kidney-tonifying Chinese herbal drugs of different concentrations for 30 min, 3 d and 28 d, respectively. The cells treated with 10% rat serum without the drugs served as the control. Flow cytometry was used to observe the changes in cell proliferation and intracellular Ca2+ concentration, and von Kossa staining employed for quantification of the mineral nodules. RESULTS: The osteoblasts obtained were positive for ALP staining and could form calcium nodules in vitro. Flow cytometry showed that the drugs at different concentrations all increased Ca2+ influx, as compared with the control cells. The drugs also increased the relative proliferation index of the osteoblasts, and high concentration of the drugs resulted in greater number of the mineral nodules in the osteoblasts (P<0.05). CONCLUSION: The kidney-tonifying Chinese herbal drugs may increase Ca2+ influx and stimulate proliferation and differentiation of adult osteoblasts in vitro.

Alkaline Phosphatase↗
PubMed2004

[Establishment of the reference panel for HIV RNA].

OBJECTIVE: To establish a national reference panel for HIV RNA diagnostic reagents. METHODS: Sera from patients with HIV infection and healthy blood donors were collected and tested for HIV and HCV antibodies and HBsAg by using ELISA. The HIV antibody positive samples with ELISA were confirmed with HIV Blot 2.2 (Genelabs). The quantitative samples for HIV RNA were calibrated with the WHO HIV RNA standard. The stability of the panel was evaluated with acceleration method. RESULTS: After screening and calibration, 8 negative samples, 8 positive samples, 3 quantitative samples, 6 sensitivity samples and 5 samples for linear analysis were composed of the national reference panel for HIV RNA. The convinced international units (IU) for the quantitative samples were obtained by seven independent calibration and the logarithm of international units for the quantitative samples (b1-b3) were less than x +/- s. The results showed that this panel may stabilize for 4 days at 4 degrees C. CONCLUSION: A national reference panel for HIV RNA reagents has been established. It may provide the basis for evaluating HIV RNA diagnostic reagents.

Blood Donors↗
PubMed2004

[Effects of silicon supply and Sphaerotheca fuliginea inoculation on resistance of cucumber seedlings against powdery mildew].

By the method of hydroponic culture, this paper studied the effects of soluble silicon (Si) supply and Sphaerotheca fuliginea inoculation on the active oxygen metabolism, SiO2 content and disease resistance of a susceptible cultivar. The results showed that the O2*- producing rate and H2O2 and MDA contents of cucumber leaf were increased by Sphaerotheca fuliginea inoculation, but reduced by the inoculation plus Si supply. The inoculation enhanced the catalase (CAT) and peroxidase (POD) activities in plant leaves but decreased their superoxide dismutase (SOD) activity, while inoculation plus Si supply increased the activities of these enzymes. Inoculation increased the scorbate (AsA) and glutathione (GSH) contents in plant leaves. The AsA content in Si-supplied plant leaves was lower than that of Si-deprived ones, whereas the GSH content was in reverse. Whether inoculated or not, the SiO2 content in Si-supplied plant leaves was significantly higher than that of Si-deprived ones. The disease index was significantly decreased by Si-supply.

Ascomycota↗
PubMed2003

Arginyl-tRNA synthetase with signature sequence KMSK from Bacillus stearothermophilus.

ArgRS (arginyl-tRNA synthetase) belongs to the class I aaRSs (aminoacyl-tRNA synthetases), though the majority of ArgRS species lack the canonical KMSK sequence characteristic of class I aaRSs. A DNA fragment of the ArgRS gene from Bacillus stearothermophilus was amplified using primers designed according to the conserved regions of known ArgRSs. Through analysis of the amplified DNA sequence and known tRNA(Arg)s with a published genomic sequence of B. stearothermophilus, the gene encoding ArgRS ( argS ') was amplified by PCR and the gene encoding tRNA(Arg) (ACG) was synthesized. ArgRS contained 557 amino acid residues including the canonical KMKS sequence. Recombinant ArgRS and tRNA(Arg) (ACG) were expressed in Escherichia coli. ArgRS purified by nickel-affinity chromatography had no ATPase activity. The kinetics of ArgRS and cross-recognition between ArgRSs and tRNA(Arg)s from B. stearothermophilus and E. coli were studied. The activities of B. stearothermophilus ArgRS mutated at Lys(382) and Lys(385) of the KMSK sequence and at Gly(136) upstream of the HIGH loop were determined. From the mutation results, we concluded that there was mutual compensation of Lys(385) and Gly(136) for the amino acid-activation activity of B. stearothermophilus ArgRS.

Adenosine Triphosphatases↗
PubMed2003

Antiangiogenic antithrombin down-regulates the expression of the proangiogenic heparan sulfate proteoglycan, perlecan, in endothelial cells.

Antithrombin, a key serpin family regulator of blood coagulation proteases, is transformed into a potent antiangiogenic factor by limited proteolysis or mild heating. Here, we show by cDNA microarray, semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), Northern blotting, and immunoblotting analyses that the expression of the proangiogenic heparan sulfate proteoglycan (HSPG), perlecan, but not other HSPGs, is dramatically down-regulated in human umbilical vein endothelial cells (HUVECs) treated with antiangiogenic cleaved and latent forms of antithrombin but not with the native form. Down-regulation of perlecan expression by cleaved and latent antithrombins was observed in both basic fibroblast growth factor (bFGF)-stimulated and unstimulated cells, whereas the antiangiogenic antithrombins inhibited the proliferation of only bFGF-stimulated HUVECs by arresting cells at the G(1) cell cycle phase. The importance of perlecan expression levels in mediating the antiproliferative effect of the antiangiogenic antithrombins was suggested by the finding that transforming growth factor-beta 1, a potent stimulator of perlecan expression in endothelial cells, blocked the down-regulation of perlecan expression and antiproliferative activity of cleaved antithrombin on endothelial cells. The previously established key role of perlecan in mediating bFGF stimulation of endothelial cell proliferation and angiogenesis suggests that a primary mechanism by which antiangiogenic antithrombins exert their effects is through the down-regulation of perlecan expression.

Antithrombins↗
PubMed2003

Increased atherosclerotic lesions in apoE mice with plasma phospholipid transfer protein overexpression.

OBJECTIVE: Plasma phospholipid transfer protein (PLTP) is involved in the metabolism of HDL and apolipoprotein B (apoB)-containing lipoproteins. Atherosclerosis susceptibility is decreased in mice with PLTP deficiency that is associated with decreased liver production of apoB-containing lipoproteins and increase in their antioxidant. To investigate additionally the effect of PLTP on the development of atherosclerosis, we overexpressed PLTP in mice. METHODS AND RESULTS: PLTP was overexpressed in apoE knockout mice using an adenovirus-associated virus (AAV)-mediated system. Plasma PLTP activity was 1.3- to 2-fold higher in mice injected with AAV-PLTP than in mice injected with control AAV-GFP, and PLTP levels were sustained during the experiment period (4 months). We show that 2-fold increased PLTP activity results in (1) a decrease in HDL cholesterol, HDL phospholipid, and apoAI levels; (2) a decrease in vitamin E contents in total plasma and in individual lipoprotein fractions; (3) an increase in lipoprotein oxidizability as assessed by copper-induced formation of conjugated dienes; (4) an increase in autoantibodies against oxidized apoB-containing particles; and (5) an increase in atherosclerosis lesions in proximal aorta. CONCLUSIONS: These observations indicate that elevated plasma PLTP levels constitute a novel, long-term risk factor for atherosclerosis.

Adenoviridae↗
PubMed2003

Prolonged survival of heart allografts transduced with AAV-CTLA4Ig.

Organ grafts transduced with gene-encoding immunosuppressive molecules are a less toxic approach to preventing graft rejection. Adenovirus vectors have been widely tested with unsatisfactory results, while adeno-associated virus (AAV) is smaller and elicits a low host humoral response. We constructed an AAV vector containing the mouse CTLA4Ig gene. B10 (H2(b)) cardiac grafts were transduced with AAV-CTLA4Ig by coronary infusion. AAV-LacZ vectors were used as reporters and controls, and the expression of beta-gal was determined by X-gal staining. Thirty percent to 40% of myocytes displayed strongly positive X-gal staining after infusion with AAV-LacZ. Additional infusion with vascular dilator reagents did not improve the transduction rate. Survival of B10 heart allografts transduced with AAV-CTLA4-Ig was significantly prolonged in C3H (H2(k)) recipients. These data demonstrate that AAV vectors can efficiently be transduced into the mouse myocardium by coronary infusion. Graft transduction with AAV-CTLA4Ig may be a novel approach to preventing allograft rejection.

Animals↗
PubMed2003

Transferrin microheterogeneity in pregnancies with preeclampsia.

BACKGROUND: It has been reported that concentrations of serum transferrin (Tf) and its highly sialylated subfraction increase in normal pregnancy. This study investigated changes in the concentrations of serum transferrin and its subfractions in preeclampsia. METHODS: The serum concentration of transferrin was determined by a standard turbidimetric assay and microheterogeneous transferrin subgroups (low sialylated, 4-sialo and highly sialylated transferrins) were assessed by crossed immuno-isoelectric focusing. RESULTS: Compared to normal pregnancy, the concentrations of total, 4-sialo and highly sialylated transferrins decreased by 27%, 16% and 38%, respectively, in severe preeclampsia, while these values did not significantly decrease in mild preeclampsia. The concentration of low sialylated transferrin involving 2-sialo- and 3-sialo-transferrins significantly decreased both in mild and severe preeclampsia, the value in severe preeclampsia was even significantly lower than that in nonpregnant women. The serum concentrations of total and highly sialylated transferrins in preeclampsia were correlated positively with infant birth weights (r=0.587 and r=0.645, respectively). CONCLUSIONS: The serum concentrations of total and highly sialylated transferrins in severe preeclampsia decrease significantly. This might have a negative impact on intrauterine growth. Additionally, the serum low sialylated transferrin decreases more sensitively in preeclampsia, although the concentration is low even in normal pregnancy.

Birth Weight↗