Biomedical subjects

Qian Chen

Publications and source records attributed to Qian Chen.

At least 73 records · Page 4Linked to original sources

PubMed2005

[The construction of recombinant AAV vector expressing HSVtk gene controlled by Tet-On and the detection of its activity].

In order to investigate the application of recombinant adeno-associated virus (rAAV) vector containing Tet regulation system and HSVtk gene in cancer gene therapy, pAAV/TRE/HSVtk/Tet-On was constructed and identified with PCR and restriction enzyme digestion. Packaging cells HEK293 were cotransfected with plasmids pAAV/TRE/HSVtk/Tet-On, pAAV-RC and pAAV-helper to produce infectious rAAV, and CsCl2 densitygradient centrifugation method was performed for purification and concentration of rAAV. The viruses were then transduced into MCF-7 cells. The results of dot blot hybridization indicate that the rAAV can transfer the target gene into MCF-7 cells. MTT assay showed that GCV could kill AAV-infected MCF-7 cells under the induction of Dox. The data demonstrated that rAAV containing Tet regulation system and HSVtk gene was successfully obtained, and could be used for further investigation of in vivo and in vitro experiments.

Cell Line, Tumor↗

PubMed2005

[Auditory brainstem response in severe obstructive sleep apnea-hypopnea syndrome children].

OBJECTIVE: To explore the characteristics of auditory brainstem response(ABR) in severe obstructive sleep apnea-hypopnea syndrome. METHOD: ABR was recorded in 37 severe OSAHS patients (OSAHS group) and 20 controls. RESULT: (1) In the OSAHS group, the latency values of waves I, III and V were (1.67+/-0.20) ms, (3.87+/-0.31) ms, (5.70+/-0.31) ms respectively. In the control group, the latency values of waves I, III and V were (1.60+/-0.11) ms, (3.81+/-0.23) ms, (5.61+/-0.23) ms respectively. A statistically significant prolongation was found in the latency values of waves I in OSAHS group compared to control group (P < 0.05). (2) When comparing to the control group, the transmission time between waves III and V was found to be prolonged and waves I and III to be shortened in the OSAHS group. Furthermore, the change was considered statistically significant (P <0.05). (3) A statistically significant elevation was found in response threshold of wave V when comparing to the control group (P < 0.05). CONCLUSION: The pathological sleepiness seen in OSAHS patients may cause ABR abnormalities, as a consequence of the chronic hypoxic and hypercapnic status occurring in the brain-stem and cochlear.

Case-Control Studies↗

PubMed2005

[Analysis of the characteristics of matching hearing aids in deaf children in Guangdong province].

OBJECTIVE: To explore the characteristics of matching hearing aids in different districts with various economic levels. METHOD: The deaf children were divided into two groups: one group came from district with poor economic level, another came from district with flourishing economic level. The age of first matching hearing aids, sex proportion, degree of hearing loss and type of hearing aids (digital/simulation) were analyzed. RESULT: (1) The average age of first matching hearing aids was 3.82 years old; male: female = 1.47:1. No significant difference was observed between two different district. (2) The proportion of deaf children whose response threshold of wave V was above 90 dBnHL was 86.36% in district with flourishing economic level, whereas it was 93.85% in district with poor economic level. (5) The proportion of deaf children whose first hearing aids were digital was 75.57% in district with flourishing economic level. It was 65.38% in district with poor economic level. CONCLUSION: A significant correlation is found between characteristics of matching hearing aids and economic level. The reason that the difference of sex proportion is enormous must be studied in further studies.

Child↗

PubMed2004

Cutting edge: bone morphogenetic protein antagonists Drm/Gremlin and Dan interact with Slits and act as negative regulators of monocyte chemotaxis.

Drm/Gremlin and Dan, two homologous secreted antagonists of bone morphogenic proteins, have been shown to regulate early development, tumorigenesis, and renal pathophysiology. In this study, we report that Drm and Dan physically and functionally interact with Slit1 and Slit2 proteins. Drm binding to Slits depends on its glycosylation and is not interfered with by bone morphogenic proteins. Importantly, Drm and Dan function as inhibitors for monocyte migration induced by stromal cell-derived factor 1alpha (SDF-1alpha) or fMLP. The inhibition of SDF-1alpha-induced monocyte chemotaxis by Dan is not due to blocking the binding of SDF-1alpha to its receptor. Thus, the results identify that Drm and Dan can interact with Slit proteins and act as inhibitors of monocyte chemotaxis, demonstrating a previously unidentified biological role for these proteins.

Animals↗

PubMed2004

Human ribonuclease A superfamily members, eosinophil-derived neurotoxin and pancreatic ribonuclease, induce dendritic cell maturation and activation.

A number of mammalian antimicrobial proteins produced by neutrophils and cells of epithelial origin have chemotactic and activating effects on host cells, including cells of the immune system. Eosinophil granules contain an antimicrobial protein known as eosinophil-derived neurotoxin (EDN), which belongs to the RNase A superfamily. EDN has antiviral and chemotactic activities in vitro. In this study, we show that EDN, and to a lesser extent human pancreatic RNase (hPR), another RNase A superfamily member, activates human dendritic cells (DCs), leading to the production of a variety of inflammatory cytokines, chemokines, growth factors, and soluble receptors. Human angiogenin, a RNase evolutionarily more distant to EDN and hPR, did not display such activating effects. Additionally, EDN and hPR also induced phenotypic and functional maturation DCs. These RNases were as efficacious as TNF-alpha, but induced a different set of cytokine mediators. Furthermore, EDN production by human macrophages could be induced by proinflammatory stimuli. The results reveal the DC-activating activity of EDN and hPR and suggest that they are likely participants of inflammatory and immune responses. A number of endogenous mediators in addition to EDN have been reported to have both chemotactic and activating effects on APCs, and can thus amplify innate and Ag-specific immune responses to danger signals. We therefore propose these mediators be considered as endogenous multifunctional immune alarmins.

Antigens, CD34↗

PubMed2004

Temporin A and related frog antimicrobial peptides use formyl peptide receptor-like 1 as a receptor to chemoattract phagocytes.

Many mammalian antimicrobial peptides (AMPs) have multiple effects on antimicrobial immunity. We found that temporin A (TA), a representative frog-derived AMP, induced the migration of human monocytes, neutrophils, and macrophages with a bell-shaped response curve in a pertussis toxin-sensitive manner, activated p44/42 MAPK, and stimulated Ca(2+) flux in monocytes, suggesting that TA is capable of chemoattracting phagocytic leukocytes by the use of a G(ialpha) protein-coupled receptor. TA-induced Ca(2+) flux in monocytes was cross-desensitized by an agonistic ligand MMK-1 specific for formyl peptide receptor-like 1 (FPRL1) and vice versa, suggesting that TA uses FPRL1 as a receptor. This conclusion was confirmed by data showing that TA selectively stimulated chemotaxis of HEK 293 cells transfected with human FPRL1 or its mouse ortholog, murine formyl peptide receptor 2. In addition, TA elicited the infiltration of neutrophils and monocytes into the injection site of mice, indicating that TA is also functionally chemotactic in vivo. Examination of two additional temporins revealed that Rana-6 was also able to attract human phagocytes using FPRL1, but temporin 1P selectively induced the migration of neutrophils using a distinct receptor. Comparison of the chemotactic and antimicrobial activities of several synthetic analogues suggested that these activities are likely to rely on different structural characteristics. Overall, the results demonstrate that certain frog-derived temporins have the capacity to chemoattract phagocytes by the use of human FPRL1 (or its orthologs in other species), providing the first evidence suggesting the potential participation of certain amphibian antimicrobial peptides in host antimicrobial immunity.

Animals↗

PubMed2004

N-Boc-L-valine-connected amidomonophosphane rhodium(I) catalyst for asymmetric arylation of N-tosylarylimines with arylboroxines.

A catalytic asymmetric arylation of sterically tuned imines with arylboroxines was developed by using N-Boc-l-valine-connected amidomonophosphane rhodium(I) catalyst in n-PrOH. The TMS group used for the steric tuning of imines is convertible to other functionalities that are applicable as a key foothold for the carbon-carbon bond-forming coupling reactions.

Boron Compounds↗

PubMed2004

Alpha-fetoprotein stimulated the expression of some oncogenes in human hepatocellular carcinoma Bel 7402 cells.

AIM: To investigate the molecular mechanism of alpha-fetoprotein (AFP) on regulating the proliferation of human hepatocellular carcinoma cells. METHODS: Alpha-fetoprotein purified from human umbilical blood was added to cultured human hepatocellular carcinoma Bel 7402 cells in vitro for various treatment periods. The expression of c-fos, c-jun, and N-ras mRNA involved in proliferation and differentiation of cells was analyzed by Northern blot, and the expression of mutative p53 and p21(ras) proteins was determined by Western blot. RESULTS: The results showed that AFP (20 mg/L) stimulated mRNA expression of these oncogenes in Bel 7402 cells. The expression of c-fos mRNA increased by 51.1%, 60.9%, 96.0%, and 25.5% at 2, 6, 12, and 24 h, respectively. The expression of c-jun and N-ras mRNA reached to the maximum which increased by 81.3% and 59.9% as compared with the control after 6 h and 24 h incubation with AFP, respectively. Western blot assay also demonstrated that AFP promoted the expression of mutative p53 and p21(ras) proteins, and the increased rate of those proteins was 13.0%, 39.9%, and 70.9%, as well as 35.2%, 102.6%, and 46.8% at 6, 12, and 24 h, respectively, as compared with the control. Both human serum albumin (the same dosage as AFP) and monoclonal anti-AFP antibody failed to stimulate the expression of these oncogenes, but anti-AFP antibody could block the functions of AFP. CONCLUSION: The data indicate that AFP can stimulate the expression of some oncogenes to enhance the proliferation of human hepatocellular carcinoma Bel 7402 cells.

Carcinoma, Hepatocellular↗

PubMed2004

Incremental multiple objective genetic algorithms.

This paper presents a new genetic algorithm approach to multiobjective optimization problems--incremental multiple objective genetic algorithms (IMOGA). Different from conventional MOGA methods, it takes each objective into consideration incrementally. The whole evolution is divided into as many phases as the number of objectives, and one more objective is considered in each phase. Each phase is composed of two stages. First, an independent population is evolved to optimize one specific objective. Second, the better-performing individuals from the single-objecive population evolved in the above stage and the multiobjective population evolved in the last phase are joined together by the operation of integration. The resulting population then becomes an initial multiobjective population, to which a multiobjective evolution based on the incremented objective set is applied. The experiment results show that, in most problems, the performance of IMOGA is better than that of three other MOGAs, NSGA-II, SPEA, and PAES. IMOGA can find more solutions during the same time span, and the quality of solutions is better.

Algorithms↗

PubMed2004

Insulin-like growth factor-I signaling is modified during chondrocyte differentiation.

Insulin-like growth factor-I (IGF-I) is a critical regulator of skeletal growth. While IGF-I has been shown to be a potent chondrocyte mitogen in vitro, its role in chondrocyte differentiation is less well characterized. We chose to study the action of IGF-I on an accepted model of chondrocyte differentiation, the ATDC5 cell line. Insulin concentrations sufficiently high to interact with the IGF-I receptor are routinely used to induce ATDC5 cells to differentiate. Therefore, we first examined the ability of IGF-I to promote chondrocyte differentiation at physiological concentrations. IGF-I could induce differentiation of these cells at concentrations below 10 nM. However, increasing IGF-I concentrations were less potent at inducing differentiation. We hypothesized that mitogenic effects of IGF-I might inhibit its differentiating effects. Indeed, the extracellular-signal-regulated kinase (ERK)-pathway inhibitor PD98059 inhibited ATDC5 cell DNA synthesis while enhancing differentiation. This suggested that the ability of IGF-I to promote both proliferation and differentiation might require that its signaling be modulated through the differentiation process. We therefore compared IGF-I-mediated ERK activation in proliferating and hypertrophic chondrocytes. IGF-I potently induced ERK activation in proliferating cells, but minimal ERK response was seen in hypertrophic cells. In contrast, IGF-I-mediated Akt activation was unchanged by differentiation, indicating intact upstream IGF-I receptor signaling. Similar findings were observed in the RCJ3.1C5.18 chondrogenic cell line and in primary chick chondrocytes. We conclude that IGF-I promotes both proliferation and differentiation of chondrocytes and that the differentiation effects of IGF-I may require uncoupling of signaling to the ERK pathway.

Animals↗

PubMed2004

Suicide gene therapy of human breast cancer in SCID mice model by the regulation of Tet-On.

BACKGROUND: RevTet-On gene expression system was used to deliver the suicide gene tk to human breast cancer cell line MCF-7 and control the tk gene expression level. The animal model of human breast cancer on severe combined immune deficiency (SCID) mice was set up to explore the suicide gene therapy by the regulation of Tet-On. METHODS: Herpes simplex virus-thymidine kinase (HSVtk) gene was inserted into the plasmid pRevTRE and the recombinant retroviral vector pRevTRE/HSVtk was constructed. Using modified calcium phosphate co-precipitation method, two transfections, pRevTRE/HSVtk and pRevTet-On were performed for MCF-7 cell line and selected by hygromycin B and G418. MCF-7 cell line that stably expressed Tet-regulated tk gene was established. HSVtk gene expression in the MCF/TRE/tk/Tet-On cell line was under the control of Doxycycline (Dox). Cell viability was also determined by MTT assay, whereas HSVtk gene expression was analyzed by reverse transcription-PCR (RT-PCR). RESULTS: MCF/TRE/tk/Tet-On cell survival rate was decreased from 100% to less than 20% when ganciclovir (GCV) concentration was increased from 0 to 1000 microg/ml at 1 microg/ml of Dox after 72 hours of GCV administration. At 1 microg/ml of GCV concentration, the cell numbers decreased from 7 x 10(4) cells/ml to 2 x 10(4) cells/ml when Dox concentration was increased from 0 to 1500 ng/ml after 72 hours culture. In addition, bystander effects were generated in vitro when 10% - 25% of transduced MCF-7 cells were mixed in untransduced MCF-7 cells. On the other hand, the human breast cancer models in SCID mice were set up. The tk gene was expressed with the regulated character after MCF/TRE/tk/Tet-On cells were implanted into the female SCID mice 7 days after Dox induction followed by intraperitoneally administration of GCV for 23 days. Subcutaneous tumors in SCID mice that were implanted with MCF/TRE/tk/Tet-On cells shrank remarkably after Dox and GCV administration as compared with the control. CONCLUSION: The human breast tumor cells (MCF-7) expressing HSVtk gene can be eradicated by administration of GCV and induced with tetracycline or its derivative Dox in vitro and in vivo.

Animals↗

PubMed2004

[A new steroidal alkaloid from the bulbus of Fritillaria wabuensia].

AIM: To investigate the chemical constituents of the bulbs of Fritillaria wabuensia. METHODS: Chromatography techniques were used to isolate the chemical constituents. EI-MS, 1HNMR, 13 CNMR and DEPT were used to determine the structures of the isolated constituents. RESULTS: Three alkaloids were isolated from the bulbs of Fritillaria wabuensia, and were identified as imperialine (I), imperialine-beta-N-oxside (II), isoverticine-beta-N-oxide (III). CONCLUSION: Isoverticine-beta-N-oxide was isolated from the bulbs of Fritillaria wabuensia for the first time. Isoverticine-beta-N-oxide is a new alkaloid.

Cevanes↗

PubMed2004

[Protective effect of tetramethylpyrazine and L-arginine on rats with acute myocardial infarction].

OBJECTIVE: To compare the protective effects of tetramethylpyrazine (TMP) alone and TMP and L-arginine (TMP-LA) combination on rats with acute myocardial infarction (AMI), and to explore its mechanism. METHODS: The rat model of AMI was established by via caudal vein injection of pituitrin. Experimental animal groups of normal, model, TMP treated and TMP-LA (via abdominal cavity and caudal vein respectively) treated groups were established. Expression of P- and E-selectin, serum creatine phosphokinase (CK) and troponin T (TnT), and marrow peroxidase (MPO) concentration in myocardial tissue were determined by immunohistochemical stain. RESULTS: As compared with the normal group, serum CK and TnT level, and MPO concentration in myocardial tissue were significantly higher in the model group (P < 0.01), with P- and E-selectin significantly up-regulated (P < 0.01). As compared with the model group, the above-mentioned parameters in the TMP or TMP-LA treated group was significantly lower (P < 0.05). CONCLUSION: Combined use of TMP and LA showed obvious synergism in treating AMI, by way of multi-link inhibition on expression of adhesive factors and decrease of leucocyte infiltration.

Animals↗

PubMed2004

[Effects of leptin on development of mouse preimplantation embryos in vitro].

OBJECTIVE: To investigate the effects of leptin on development of mouse preimplantation embryos in vitro. METHODS: (1) Groups of 2-cell stage embryos randomly selected were placed in drops of CZB medium with or without recombinant leptin (10, 50, 100 and 500 ng/ml) and were cultured to the hatched blastocyst stage, and then embryo-transfer was carried out and the implantation rate was observed and determined. (2) Groups of 2-cell stage embryos randomly selected were placed in drops of leptin free CZB medium and cultured to morula stage. Then we changed the medium, randomized the embryos into CZB medium with or without recombinant leptin (10, 50, 100 and 500 ng/ml), and cultured them to the hatched blastocyst stage. RESULTS: Addition of leptin to embryo culture media promoted the development from 2-cell stage embryo to morula, blastocyst and hatched blastocyst and improved the implantation rate. Leptin at 0, 10, 50 ng/ml concentrations caused a dose-dependent promotion, nevertheless Leptin at even higher concentrations (100 and 500 ng/ml) only brought on the same promotion as what the Leptin at concentration of 50 ng/ml did (P>0.05). Addition of leptin to embryo culture media seemed to have no effects on the in vitro development from morula to blastocyst and hatched blastocyst. CONCLUSION: Leptin plays an important role in the development of preimplantation embryo. It can promote embryo development and embryo implantation.

Animals↗

PubMed2004

[Effect of concentration of circulating luteinizing hormone in late-follicle phase on the outcome of in vitro fertilization for normogonadotrophic women].

OBJECTIVE: To evaluate the impact of the concentration of circulating luteinizing hormone (LH) in the late-follicle phase on the outcome of in vitro fertilization for normogonadotrophic women. METHODS: Intracytoplasmic sperm injection treatment was conducted in 432 consecutive cycles of normogonadotrophic women. A stimulation protocol with mid-luteal gonadotropin-releasing hormone (GnRH) agonist down-regulation and ovarian stimulation with follicle stimulating hormone (FSH) was used in all cycles. hMG was added when a follicle of > or = 14 mm was present (FSH + hMG group), not in the control group (FSH-alone). LH and oestradiol concentration in the serum on hCG day were detected. Based on LH levels, patients in the FSH + hMG group were again divided into four subgroups: LH < or = 1, 1 < LH < or = 2, 2 < LH < or = 3, and 3 < LH < or = 10 IU/L. RESULTS: Oestradiol concentration on the day of hCG injection in the FSH + hMG group was higher than that in the FSH-alone group [(3435.51 +/- 2029.01) pg/ml vs (2620.62 +/- 1604.80) pg/ml, P < 0.05]. More embryos were transferred in the FSH-alone group than in the FSH + hMG group [(2.77 +/- 0.45) vs (2.22 +/- 0.46), P <0.001]. Fertilization rate, implantation rate, and clinical pregnancy rate were similar between the FSH-alone group and the FSH + hMG group (77.52% vs 78.31%, 41.42% vs 41.68%, 64.56% vs 62.64%, P > 0.05), as well as among the four subgroups of the FSH + hMG group (P > 0.05). CONCLUSION: The adding of suitable amount of hMG and physiologically limited LH concentration in the late-follicle phase have no negative effect on the outcome of in vitro fertilization/intracytoplasmic sperm injection for normogonadotrophic women.

Adult↗

PubMed2004

[Retroviral vector-mediated HSVtk gene expression and acquisition of high titer recombinant virus].

OBJECTIVE: To explore the HSVtk gene expression mediated by the retroviral vector and to obtain high titer recombinant retroviral virus. METHODS: The recombinant vector pRevTRE/HSVtk was constructed by inserting HSVtk gene into pRevTRE. The recombinant retrovirus, which was produced from cloned PA317 cells screened by hygromycin B after "micro-pingpong" technique transferring with pRevTRE/HSVtk plasmids DNA by using modified calcium phosphate precipitation method. HSVtk gene expression was performed on target cells and virus titers were detected in different cultured temper, time and sodium butyrate concentration. RESULTS: The recombinant retroviral vector pRevTRE/HSVtk was constructed and HSVtk gene expression was detected on target cells after they were infected with the recombinant retrovirus. CONCLUSION: High titer of retroviruses could be obtained in the culture medium of PA317 cell line through "micro-pingpong" technique at 30 hours and 10 mmol/L sodium butyrate concentration followed by frozen ultrafiltration.

Animals↗

PubMed2004

[Analyze of the clinical characteristics in children with the severe abnormal auditory brainstem response and normal distortion product otoacoustic emission].

OBJECTIVE: To explore the clinic and audiological characteristics of auditory neuropathy in children. METHODS: Between 2002 and 2004, ninety-eight cases with the severe abnormal results of ABR and the normal results of DPOAE were enrolled in the study group. The mean patient age was 9 months, with a range of 1 month to 5 years. According to the evaluation of pediatric neurologist, the high-risk factors of psychomotor development retardation were statistically analyzed whether the cases were accompanied by psychomotor development retardation or not. The cases with abnormal results of ABR and DPOAE and without abnormal conductive function were selected as the cochlea lesion group. Some same age children without hearing loss were subjected as normal control group. RESULTS: The psychomotor development retardation was performed in 83.67% of cases. Hypercholesterolemia of newborn was the common high-risk factor of psychomotor development retardation (43.88% ). Severe abnormal results of ABR were occurred in 66. 07% of ears. Prolonged latency of wave I - V ABR and acoustic stapedius reflex were observed in few cases. The DPOAE amplitudes at intermediate and high frequencies were normal or slightly descending. Occurring rate of DPOAE at intermediate and high frequencies was the same as in normal control group. CONCLUSIONS: Hypercholesterolemia of newborn is the most common cause of auditory neuropathy. The auditory test results are various in children with auditory neuropathy. This character is different from it in adults.

Audiometry, Pure-Tone↗

PubMed2003

Structure determination, apoptosis induction, and telomerase inhibition of CFP-2, a novel lichenin from Cladonia furcata.

A great deal of experimental evidence has accumulated in the past several decades, suggesting that polysaccharides have wide bioactivities. Cladonia furcata polysaccharide, CFP-2, a water-soluble lichenin with a mean Mr 7.6 x 10(4), was first obtained by 0.25 M NaOH solution extraction, ethanol precipitation, DEAE-cellulose, and Sephadex G-200 column chromatography. Gas chromatography of acid hydrolyzate of CFP-2 suggested that it was composed of D-glucose, D-galactose, and D-mannose in the molar ratios of 8:1:1. Periodate oxidation, Smith degradation, IR, and NMR spectroscopy analysis revealed that CFP-2 had a backbone consisting of alpha-(1-->3) and alpha-(1-->4)-linked D-glucopyranosyl residues substituted at O-6 with beta-(1-->6)-linked D-galactopyranosyl residue and alpha-(1-->6)-linked D-mannopyranosyl residue. CFP-2 was able to reduce viability of cultured HL-60 and K562 cells. The antiproliferative properties of CFP-2 appeared to be attributable to its induction of apoptotic cell death as determined by ultrastructural change, internucleosomal DNA fragmentation, and increased proportion of the subdiploid cell population. To elucidate molecular events in the apoptosis, protein expressions of Bcl-2, Bax, Fas, and FasL were measured by Western blotting using specific antibodies in HL-60 cells. The level of Bcl-2 remained largely unchanged, but the Bax, Fas, and FasL expression showed up-regulation. Moreover, the telomerase activity analyzed by TRAP-ELISA assay in HL-60 cells treated with CFP-2 decreased as compared with the untreated control cells. These results suggest that CFP-2 could have a possible cancer therapeutic potential.

Apoptosis↗