Biomedical subjects

Qun He

Publications and source records attributed to Qun He.

At least 19 recordsLinked to original sources

PubMed2006

Potential bridges for HIV infection to men who have sex with men in Guangzhou, China.

To assess the potential for HIV acquisition among men who have sex with men (MSM) in Guangzhou, China, we conducted a cross-sectional, anonymous, face-to-face survey of MSM in the metropolitan area of Guangzhou, China. As a pilot recruitment for a cohort study, participants were recruited by convenience sampling through newspaper and television advertising, website information, and respondent referral. Blood samples were tested for HIV, hepatitis B (HBV), hepatitis C (HCV), and syphilis. Client-centered HIV and STD counseling was provided.A total of 201 MSM were interviewed and 200 blood samples were tested. The prevalence of HIV antibody was 0% (97.5% CI 0-1.8%); 17.5% of MSM were HBV surface antigen positive; 1.0% had HCV antibodies; 10.5% had antibodies to syphilis. Syphilis seropositivity was associated with sex with a foreign MSM in the last six months and 10.4% reported sex with a foreign MSM overall. The majority (54.7%) reported unprotected anal sex with other men. Nearly one-third (31.8%) had regular female partners; 25.9% were currently married to a woman; 6% had casual female partners; 4.5% had sex with a female sex worker; 4.5% had sex with a male sex worker; and 12.9% had unprotected vaginal sex and unprotected anal sex with a man in the past six months. Only one MSM reported injection drug use (0.5%). The currently low prevalence of HIV but high level of unprotected anal sex, high prevalence of syphilis infection, and sexual networks that include foreign MSM point to a transient window for HIV prevention among MSM in Guangzhou. We recognize challenges to recruiting a representative sample of MSM and retaining them in longitudinal cohort studies.

Adolescent↗

PubMed2006

Development of quartz-crystal-microbalance-based immunosensor array for clinical immunophenotyping of acute leukemias.

An integrated piezoelectric immunosensor array has been developed to immunophenotype acute leukemias in clinic. Each quartz crystal microbalance (QCM) was fabricated with plasma-polymerized film of n-butylamine, nanogold particles, and protein A (PA) to be used to immobilize antibodies in orientation. Leukemic lineage-associated monoclonal antibodies were separately immobilized onto the nanogold-PA-modified surface of the crystals, which were constructed by a 2 x 2 type of probes forming a QCM-based immunosensor array. The main detection conditions were investigated, including the immobilization amount of antibodies, pH, immunoreaction time, sample dilution ratio, etc. The immunophenotyping feasibility of the new technique was investigated through simultaneously analyzing Jurkat cells by the immunosensor array method, immunohistochemistry, and flow cytometry. It was found that the developed technique could readily identify leukemia samples in 5 min and might monitor dynamically the immunoreaction processes. Moreover, comparison studies were carried out for CD antigens expressed on the nucleated cells isolated from 96 acute leukemic patients and 24 normal subjects using the QCM-based immunosensor method and the fluoroimmunoassay. Results obtained by immunophenotyping patients' samples with the immunosensor-based method achieved the rate of 88.93% in 768 groups of numerical data, where no significant statistical difference was observed between the two methods when checked by chi2 analysis (chi2 = 3.4, p > 0.05). This new immunosensor array showed the merits of high sensitivity, high specificity, good reproducibility, easy operation, and low cost. The results of specimen evaluation indicated that it might be clinically suitable for quantifying human differentiated leukocytes and immunophenotyping of acute leukemias.

Acute Disease↗

PubMed2006

Cytokeratin 20 and Ki-67 to distinguish carcinoma in situ from flat non-neoplastic urothelium.

Urothelial carcinoma in situ (CIS) is a high-grade neoplasm and an indicator of recurrence and progression that requires specific treatment. The distinction of CIS from flat non-neoplastic urothelium, in particular dysplasia, on the basis of histologic features is often difficult, and this study aims to validate cytokeratin 20 (CK20) and Ki-67 as discriminatory markers for this purpose. Immunostaining of these markers was applied to 26 cases of CIS, 14 atypia of unknown significance, 4 dysplasia, 6 normal, and 9 hyperplastic urothelium. CIS showed CK20 staining of deep urothelial cells in 23/26 CIS compared with restricted staining in surface cells in all non-neoplastic lesions. CIS had significantly increased Ki-67 index with a mean of 53.37% compared with that of non-neoplastic urothelium, which was <10% (P<0.0001). The proliferating cells were distributed randomly in CIS, whereas in non-neoplastic urothelium, staining was confined to the basal layer. Among the cases of atypia, 3/14 displayed deep staining for CK20 and 6/14 had elevated Ki-67 counts. In dysplasia similar findings were present in 1/4 and 2/4 cases, respectively. These findings suggest that CK20 and Ki-67 are objective markers to distinguish CIS from non-neoplastic urothelium. In cases of "atypia of unknown significance" and "dysplasia," positivity for both markers should raise the possibility of CIS or preneoplastic change and identify those cases for follow-up.

Biomarkers, Tumor↗

PubMed2006

[HLA-DQA1 genotyping by using oligonucleotide microarrays].

In order to fabricate the HLA-DQA1 genotyping chip and develop an integrated, parallel technical platform to type HLA system, a pair of primers and a set of probes were designed according to the sequences of HLA-DQA1 exon 2, where the polymorphism is concentrated. The oligonucleotide chip was made with the methods developed in our laboratory. The target DNA was asymmetrically amplified with the labeled sense primer. The signals were scanned and analyzed after the hybridization between microarray and PCR product. The allele types of the samples were identified. The result was verified by the standard DNA and DNA sequencing. The results showed that the genotyping was successfully carried out in 50 standard DNA samples and 50 clinical samples. Among them, results of the 50 standard DNA samples matched their templates. In the other 50 samples, results of the randomly selected 10 matched their sequencing results except that two of them got the incompletely result. In reproducible tests, the signal reappear rate was 95%. It is concluded that HLA-DQA1 genotyping by using our array system is simple and convenient with satisfied accuracy and reproducibility.

Genotype↗

PubMed2005

The COP9 signalosome regulates the Neurospora circadian clock by controlling the stability of the SCFFWD-1 complex.

The COP9 signalosome (CSN) promotes the function of SCF-type cullin-based ubiquitin ligase complexes in vivo. Paradoxically, removal of the Nedd8 modification of cullins by CSN inhibits the ubiquitin ligase activity of SCF complexes in vitro. Ubiquitination-mediated degradation of the Neurospora circadian clock protein FREQUENCY (FRQ) is critical for clock function. Ubiquitination of FRQ requires FWD-1, the substrate-recruiting subunit of an SCF complex. Here we show that disruption of a subunit of CSN (csn-2) impairs the degradation of FRQ and compromises its normal circadian expression. A FRQ-independent oscillator drives conidiation in the csn-2 mutant, resulting in a 2-d conidiation rhythm that persists in constant darkness (DD), constant light (LL), light-to-dark (LD) transitions, and temperature cycles. Strikingly, the levels of FWD-1 are drastically reduced in csn-2 mutant, explaining the impaired degradation of FRQ. Reduction of FWD-1 levels in the mutant requires its F-box, suggesting that its degradation is due to autoubiquitination. In addition, SKP-1 and CUL-1 of the SCF(FWD-1) complex are also unstable in the mutant. Therefore, our results establish an important role of CSN in the circadian clock of Neurospora. Our findings also reconcile the CSN paradox and suggest that a major function of CSN is to maintain the stability of SCF ubiquitin ligases in vivo.

Animals↗

PubMed2005

A new 2-aminosteroid induces cellular differentiation and upregulates the expression of MafB and Egr-1 genes respectively in HL-60 and K562 leukemia cells.

BACKGROUND: In previous work, we suggested that some 2-aminosteroids inhibited proliferation and induced differentiation of both human and murine leukemia cells. Here, we reported the actions of another new 2-aminosteroid designated as H89712 on human leukemia cells. METHODS: Cell colony counting and MTT assay were used to determine proliferation. Cell morphology, histochemical staining, UV detection and cytometry were used to determine differentiation. RT-PCR was used to detect gene expression. Standard statistical method was used to analyze data. RESULTS: H89712 inhibited proliferation of HL-60 leukemia cells and the inhibition percentage in MTT assay was 18% at the dose of 10(-8) mol/L and 65% at the dose of 10(-5) mol/L, respectively. The inhibition for HL-60 in colony assay was 23% at the dose of 10(-8) mol/L and 96% at the dose of 10(-5) mol/L, respectively. H89712 also induced HL-60 cells toward macrophage-like differentiation. It was verified by flow cytometry that the percentage of positive CD14 expression in differentiated HL-60 cells was about 9 times higher than that of the control at the dose of 10(-8) mol/L and 20 times higher than that of the control at the dose of 10(-5) mol/L respectively, and this action involved upregulation of MafB gene in HL-60 leukemia cells. On the other hand, H89712 inhibited proliferation of K562 leukemia cells and the inhibition of K562 leukemia cells in MTT assay was shown by 34% at the dose of 10(-8) mol/L and 88% at the dose of 10(-5) mol/L respectively. The inhibition of K562 leukemia cells in colony assay was 53% at the dose of 10(-8) mol/L and 100% at the dose of 10(-5) mol/L respectively. H89712 also induced K562 cells toward erythroid-like differentiation and it was verified by flow cytometry that the percentage of positive CD71 expression in differentiated K562 cells was about 9 times higher than that of the control at the dose of 10(-8) mol/L and 16 times higher than that of the control at the dose of 10(-5) mol/L respectively. This action was related to upregulation of Egr-1 gene in K562 leukemia cells. CONCLUSIONS: Our results showed the important roles played by MafB in macrophage differentiation and Egr-1 in erythroid differentiation of human myeloid leukemia cells.

Cell Differentiation↗

PubMed2005

[Differentiation-inducing effects of perphenazine on K562 leukemia cells].

OBJECTIVE: To determine the differentiation-inducing effects of perphenazine on K562 leukemia cells. METHODS: Differentiation-Inducing effects of a phenothiazine perphenazine were evaluated by proliferation, morphology and function of K562 cells. We evaluated the effects of perphenazine on K562 cells proliferation by cellular enumeration in liquid culture assay, MTT assay and clony formation assay, the morphology by Wight-Gimesa staining, and the function by detecting CD71 through flow cytometry. RESULTS: Perphenazine enhanced the expression of CD71 on K562 cells and increased Hb content in K562 cells, while inhibited the proliferation of K562 cells. K562 cells showed differentiation morphology after the drug treatment. CONCLUSION: Perphenazine possessed differentiation-inducing effects on K562 cells.

Cell Transformation, Neoplastic↗

PubMed2005

[Effects of prazosin on the proliferation and apoptosis of K562 leukemia cells].

OBJECTIVE: To investigate the effects of prazosin on the proliferation and apoptosis of human leukemia cell line (K562). METHODS: The effects of prazosin on the proliferation of K562 cells were evaluated by liquid culture assay, MTT assay and colony formation assay. Prazosin induced K562 cells toward apoptosis and this was verified by cellular morphology, Hoechst33258 fluorescence staining and flow cytometry respectively. RESULTS: The proliferation of K562 leukemia cells was inhibited by prazosin in a dose-dependent manner. With prazosin (5 x 10(-6) mol/L), the apoptosis cells could be observed morphologically, or by Hoechst 33258 fluorescence staining and flow cytometry. CONCLUSION: Prazosin can inhibit the proliferation of K562 cells and induce the apoptosis of K562 cells.

Adrenergic alpha-Antagonists↗

PubMed2005

[Mechanism of lithium chloride-induced proliferation inhibition and apoptosis of K562 leukemic cells].

To investigate the mechanism of proliferation inhibition and apoptosis of K562 leukemia cells by lithium chloride (LiCl), after K562 cells were treated with LiCl (30 mmol/L) cell cycle was examined by flow cytometry (FCM) and the expression of bcr/abl fusion gene mRNA was evaluated by RT-PCR. The intracellular Li(+) concentrations of K562 cells were determined at different time after treated with 30 mmol/L LiCl and the effects of TTX and FSK on intracellular Li(+) concentrations of K562 cells were also detected by atomic absorption spectrometry. The effects of TTX and FSK on LiCl-induced growth inhibition of K562 cells were determined by cell counting in liquid culture. The results showed that LiCl (30 mmol/L) caused a sustained arrest in G(2)/M cell cycle and down-regulated the bcr/abl mRNA expression in K562 cells, the intracellular Li(+) concentration of K562 cells increased at 30 minutes after treated with 30 mmol/L LiCl and reached apex at 2 hours, thereafter, gradually decreased and balanced at 4 hours after the treatment. If either Na(+) channel was pre-blocked with TTX or K(+) channel was pre-blocked with FSK, the intracellular Li(+) concentrations of K562 cells treated with 30 mmol/L LiCl were higher than that in the cells just treated with LiCl without pre-blocking. Furthermore, after pre-blocking either Na(+) channel with TTX or K(+) channel with FSK, the inhibition rate of K562 cell growth by 30 mmol/L LiCl could be increased. It is concluded that the mechanism of proliferation inhibition and apoptosis of K562 leukemia cells induced by LiCl is probably related with the G(2)/M cell cycle arrest, the bcr/abl mRNA expression down-regulation and the status of Na(+), K(+), or Li(+) ion channels on K562 leukemia cells.

Antineoplastic Agents↗

PubMed2004

Regulation of the Neurospora circadian clock by an RNA helicase.

The eukaryotic circadian oscillators consist of autoregulatory negative-feedback loops. FRQ, WC-1, and WC-2 are three known components of the negative-feedback loop of the Neurospora circadian oscillator. FRQ represses its own transcription by interacting with the WC-1/WC-2 complex and inhibiting WC's role in transcriptional activation. Here we show that all FRQ associates with FRH, an essential DEAD box-containing RNA helicase in Neurospora. The budding yeast homolog of FRH, Dob1p/Mtr4p, is a cofactor of exosome, an important regulator of RNA metabolism in eukaryotes. Down-regulation of FRH by inducible expression of a hairpin RNA leads to low levels of FRQ but high levels of frq RNA and the abolishment of circadian rhythmicities. FRH is associated with the WC complex and this interaction is maintained in a frq null strain. Disruption of the FRQ-FRH complex by deleting a domain in FRQ eliminates the FRQ-WC interaction, suggesting that FRH mediates the interaction between FRQ and the WC complex. These data demonstrate that FRH is an essential component in the circadian negative-feedback loop and reveal an unexpected role of an RNA helicase in regulating gene transcription.

Circadian Rhythm↗

PubMed2004

Distinct roles for PP1 and PP2A in the Neurospora circadian clock.

Phosphorylation of the Neurospora circadian clock protein FREQUENCY by several kinases promotes its degradation and is important for the function of the circadian feedback loop. Here, we show that FRQ is less stable in a ppp-1 (catalytic subunit of PP1) mutant, resulting in its advanced phase and short period. In contrast, FRQ stability is not altered in a rgb-1 (a regulatory subunit of PP2A) mutant, but levels of frq protein and mRNA are low, resulting in a low-amplitude and long-period oscillation of the clock. Furthermore, PP1 and PP2A expressed in Neurospora can dephosphorylate the endogenous FRQ in vitro, suggesting that these two phosphatases may differentially regulate FRQ and, consequently, the behavior of the circadian clock.

Catalytic Domain↗

PubMed2004

[Quantitation and detection of deletion in tumor mitochondrial DNA by microarray technique].

OBJECTIVE: To develop a method to rapidly quantitate and detect deletion of mitochondrial DNA (mtDNA) by microarray technique as a tool to study its relationship to tumorigenesis. METHODS: A modified PCR was used to amplify full length mtDNA sequence in two samples of normal human blood leukocytes and five samples of gastric cancerous tissues, which were simultaneously labeled with fluorescin. The amplified products were verified by polyacrylamide gel electrophoresis (PAGE) and silver staining. Then, 17 pairs of overlapping primers of mtDNA were designed and their PCR products were used as mitochondrial probes. They were spotted onto amino-slides as microarray and hybridized. Hybridization image was scanned with GeneTAC laser, mtDNA copy number was counted by ScanAnalyzer software. RESULTS: PAGE analysis showed that the designed probes were quite reasonable and strongly specific. The modified PCR method was efficient to amplify the whole mitochondrial genome with high-yield specific bands. The hybridizing spots were distinct, and background was clear. The signals of negative probes were close to those of background, and there was no significant difference between them (P > 0.05). The results were identical to those in the designed experiment. There were no significant differences between the results when the same sample of blood leucocytes or cancer tissues repeatedly examined with the same positive probes (P > 0.05), while there were significant differences when different types of samples were examined (P < 0.01). The hybridizing signals were stable and most of the data distributed in the range of mean +/- 2xSD. CONCLUSION: The method here reported can rapidly, correctly and massively determine whether there exist special deletion and/or quantitative changes of mtDNA in patients with tumors. It will be helpful for the study of the relationship between mtDNA alteration and tumor development.

DNA, Mitochondrial↗

PubMed2004

[Evaluation of a pilot study on needle and syringe exchange program among injecting drug users in a community in Guangdong, China].

OBJECTIVE: To evaluate the feasibility and effectiveness of needle and syringe exchange program among a community of injecting drug users (IDUs) on AIDS prevention. METHODS: A quasi-experiment design was used in a controlled community intervention study. Needle and syringe exchange program was implemented for 10 months in IDUs of an intervention community, including peer education and health education, provision of free needles and syringes, and collecting back of used needles and syringes by trained peer educators and local health workers, whereas no intervention measure in a control community was instituted. Interviews with IDUs were conducted before and after intervention with a snowballing strategy to evaluate its effectiveness. RESULTS: A total of 428 and 429 IDUs were interviewed with structured questionnaire before and after intervention in intervention and control communities, respectively. Results revealed that awareness of HIV-related knowledge increased from 29.4% to 58.7% in the intervention community. Multivariate logistic regression analysis showed that awareness of HIV-related knowledge was higher in those who had read health education materials (OR = 2.93, 95% CI 2.12 - 4.04). As compared with the baseline data, frequency of sharing needles and syringes in past 30 days in the intervention community decreased from 48.9% to 20.4% in before intervention community (chi(2) = 41.02, P = 0.001), whereas there was no significant change in the control community. The causes of sharing needles and syringes in the intervention community included 'disable to get needle and syringe during the night', 'lack of needle and syringe when injecting at friend's home', 'not daring to buy needle and syringe for fear of being arrested' and 'no money to buy needle and syringe', declined markedly. CONCLUSIONS: Needle and syringe exchange program was feasible and effective in reducing their risky drug injecting behavior among IDUs in communities. Such strategy should be adopted in the country to reduce rapid spread of HIV.

Adult↗

PubMed2004

[A new blocking method for DNA chip].

Suggested a new blocking method for DNA microarray: 1-iodo-propane. We compared the difference between the two block reagents and the blocking results in different blocking time. The results showed that 1-I-propane is batter-blocking reagent than succinic anhydride in DNA chip. 1h blocking time is enough for blocking.

Hydrocarbons, Iodinated↗

PubMed2004

[Effects of an antioxidant (An7845) on the proliferation and apoptosis of K562 leukemia cells].

OBJECTIVE: To determine the effects of an antioxidant (An7845) on the proliferation inhibition and apoptosis induction of a human leukemia cell line (K562). METHODS: We evaluated the effects of An7845 on K562 cell proliferation by cellular enumeration in liquid culture assay, MTT assay and colony formation assay. We also verified the effects of An7845 on K562 cell apoptosis by cellular morphology and the DNA fragments appeared in agarose gel electrophoresis. RESULTS: The proliferation of K562 leukemia cells was inhibited by An7845 (5 x 10(-8) - 5 x 10(5) mol/L) in a dose-dependent manner. K562 cells were induced toward apoptosis by An7845 (5 x 10(-7) mol/L). CONCLUSION: An7845 can effectively inhibit the proliferation and induce the apoptosis of K562 leukemia cells.

Antioxidants↗

PubMed2003

FWD1-mediated degradation of FREQUENCY in Neurospora establishes a conserved mechanism for circadian clock regulation.

Phosphorylation of the Neurospora circadian clock protein FREQUENCY (FRQ) regulates its degradation and the proper function of the clock. The mechanism by which FRQ undergoes degradation has not been established. Here we show that FRQ is likely ubiquitylated in vivo, and its proper degradation requires FWD1, an F-box/WD-40 repeat-containing protein. In the fwd1 disruption strains, FRQ degradation is severely impaired, resulting in the accumulation of hyperphosphorylated FRQ. Furthermore, the circadian rhythms of gene expression and the circadian conidiation rhythms are abolished in these fwd1 mutants. Finally, FRQ and FWD1 interact physically in vivo, suggesting that FWD1 is the substrate-recruiting subunit of an SCF-type ubiquitin ligase responsible for FRQ ubiquitylation and degradation. Together with the recent finding that Slimb (the Drosophila homolog of FWD1) is involved in the degradation of the Period protein in flies, our results indicate that FWD1 regulates the degradation of FRQ in Neurospora and is an evolutionarily conserved component of the eukaryotic circadian clock.

Amino Acid Sequence↗

PubMed2003

[Effects of lithium chloride on the proliferation and apoptosis of K562 leukemia cells].

OBJECTIVE: To investigate the effects of lithium chloride on the proliferation and apoptosis of human leukemia cell line (K562). METHODS: The effects of lithium chloride on the proliferation of K562 leukemia cells were evaluated by liquid culture assay, MTT assay, and colony formation assay. The effects of lithium chloride on the apoptosis of K562 leukemia cell were verified by cellular morphology and the agarose gel electrophoresis of DNA fragments. RESULTS: 1. The proliferation of K562 leukemia cells was inhibited by lithium chloride (10-50 mmol/L) in a dose-dependent manner. 2. With lithium chloride (30 mmol/L), the apoptosis cells could be observed in cellular morphology, and DNA ladder was also observed in agarose gel electrophoresis. CONCLUSION: Lithium chloride can inhibit the proliferation of K562 cells and cause the apoptosis of K562 cells.

Antineoplastic Agents↗

PubMed2003

[Optimization of cDNA microarray fabrication].

To optimize and screen the most suitable target gene length,concentration and printing solution in cDNA microarray, housekeeping genes, such as beta actin and GAPDH, were selected as targets and hepatitis B virus gene as negative control. The RT-PCR primers that spanned at least one intron and whose products were at between 189 bp and 1078 bp were designed with primer premier 5.0, so did the hepatitis B virus gene PCR primer. After polymerase chain reaction, the products were purified with ethanol and dissolved in 3xSSC, 50% DMSO and 0.5 mol/L carbonate buffer(pH=9.0)respectively. The concentrations of target genes were adjusted at 0.5 microg/microL, 1.0 microg/microL and 1.5 microg/microL. The hybridization signals had a good specificity. No signal showed in either negative control (HBV) or blank control (printing solution only). There was no significant difference in target gene lengths. The P value of beta actin (189 bp,491 bp,974 bp) and GAPDH (227 bp,552 bp,1078 bp) was 0.378 and 0.866 respectively. There was no significant difference among concentrations(P=0.648),too. However, the higher the concentration was, the stronger the signals would be. Among the three kinds of printing solution, 50% DMSO was the best (P=0.0001), while the other two had no difference by multi-comparison (P=0.142). The target gene at length between 200 bp and 1000 bp has got the same hybridization signals.50% DMSO printing solution and the target gene concentration of 0.5 microg/microl are suitable for good hybridization.

English Abstract↗