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Biomedical subjects

Yun He

Publications and source records attributed to Yun He.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Construction of short hairpin RNA vector of inhibiting poly ADP-ribose polymerase activity].

OBJECTIVE: To construct expressing vector of short hairpin RNA (shRNA) in order to inhibit human PARP1 activity. METHODS: 2 pairs of 64 base oligos for hairpin RNA expression which targeted PARP1 gene were chemically synthesized and annealed then ligased with pSIREN-RetroQ vector with BamH II and EcoR I . Cut by EcoR t and Bgl II, shRNA and its upstream U6, which have 330 bp, were inserted into the same treated pEGFP-C1 vecter to construct GFP expression plasmids that inhibited hPARP1 protein shRNA plasmid (pEGFP-C1P). Oligos with a scrambled sequence were used as a negative control. RESULTS: Recombinant pEGFP-C1P1, pEGFP-C1P2 and pEGFP-C1N vectors was identified by digestion with EcoR I and Bgl II and confirmed by sequencing analysis with U6 primer. The results demonstrated that the 330 bp had been inserted into the expected site. Furthermore, the insertion sequence was exactly correct. CONCLUSION: pEGFP-C1-shRNA system has been constructed successfully. This will facilitate the study of PARP1's DNA repairing function.

Genetic Vectors↗
PubMed2006

[Effects of overexpression of human pol-beta on cellular response to DNA damage].

OBJECTIVE: To investigate the biological effects of overexpression of the human DNA polymerase (pol-beta) on cellular response to DNA damage. METHODS: The cell strain HLFbeta from the stable overexpression of the human pol-beta was contaminated with methyl methanesulfonate (MMS) for investigating the effects of the pol-beta on the cellular responses to DNA damage on the aspects such as the DNA damage, the cell cycle and the induced mutation rate. RESULTS: The cell HLFbeta from the stable overexpression of the human pol-beta was obtained through the screening. The cellular response to DNA damage of HLFbeta induced by the MMS in the intermediate and high dosage group (ranging from 0.5 to 0.8 mmol/L) was significantly lower than that in the control group. The analysis for the cell cycle distribution showed that both the two types of cells contaminated by MMS had retardation at G(2) phase. In the HLFbeta group, the cells had the obvious G(2) phase retardation and 49.0% of the cells were retarded at G(1) phase as well when the MMS was increased to 0.5 mmol/L while in the control, only 20.1% of the cells were retarded at the G(1) phase when the same dosage of MMS was administered. Moreover, the MMS-induced mutagenesis in HLFbeta was increased from 4.5 x 10(-6) to 8.2 x 10(-6), significantly higher than that in the control group (P < 0.05). CONCLUSION: High Pol-beta level decreases cellular DNA damage induced by MMS. Nevertheless, the overexpression of Pol-beta can also increase error-prone DNA synthesis during DNA repair process.

Cell Cycle↗
PubMed2006

[Vector-mediated RNA interference of DNA polymerase beta in human bronchial epithelial cells].

OBJECTIVE: To knock down the expression of polymerase beta gene in human bronchial epithelial cells with technology of vector-mediated RNA interference (RNAi), to provide research tool for the study on the functions and mechanisms of polymerase beta in repairing of DNA damaged by environmental chemical pollutants (ECPs). METHODS: Technology of molecular clone was used to construct the recombination vector of "pEGFP-C1-U6-dsRNA" for the polymerase beta RNAi. The recombinants were transfected into human bronchial epithelial cells with kit of liperfectamine 2000. The control groups included normal human bronchial epithelial cells and human bronchial epithelial cells transfected with "pEGFP-Cl1. Cells were screened by G418, then technology of fluorescence microscopy imaging was used to observe the result of transrfection. The expresison level of polymerase beta was detected by Western blotting. RESULTS: The expression level of polymerase beta in human bronchial epithelial cells transfected with the recombinant of "pEGFP-C1-U6-dsRNA" was about 17.3% of what in the normal cells. CONCLUSION: The RNAi of polymerase beta gene in human bronchial epithelial cells was successful.

Bronchi↗
PubMed2006

[Coinfection with HBV and HCV in 128 AIDS patients infected through blood transmission].

OBJECTIVE: To analyze the clinical features of 128 acquired immunodeficiency syndrome (AIDS) patients infected through blood transmission who were coinfected with hepatitis B virus (HBV) and hepatitis C virus (HCV). METHODS: The prevalence, liver functions, and some immunological profiles of 128 AIDS patients coinfected with HBV and HCV were retrospectively analyzed. RESULTS: Among the 128 AIDS patients, 107 (83.6%) were coinfected with HCV, among which 40 (31.3%) patients had abnormal liver functions or liver damage and 15 (11.7%) patients experienced hepatitis symptoms. Three (2.3%) AIDS patients were singly coinfected with HBV, and all of them had abnormal liver functions and hepatitis symptoms. Seven (5.5%) patients were coinfected with HIV/HCV/HBV and none of them had abnormal liver functions or hepatitis symptoms. Eleven (8.6%) patients were only infected with HIV. CONCLUSIONS: The prevalence of blood-transmitted HIV patients coinfected with HCV is higher than with HBV. The clinical outcomes of HIV coinfection with HCV and HBV are different.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Predicting protein secondary structure and solvent accessibility with an improved multiple linear regression method.

We have improved the multiple linear regression (MLR) algorithm for protein secondary structure prediction by combining it with the evolutionary information provided by multiple sequence alignment of PSI-BLAST. On the CB513 dataset, the three states average overall per-residue accuracy, Q(3), reached 76.4%, while segment overlap accuracy, SOV99, reached 73.2%, using a rigorous jackknife procedure and the strictest reduction of eight states DSSP definition to three states. This represents an improvement of approximately 5% on overall per-residue accuracy compared with previous work. The relative solvent accessibility prediction also benefited from this combination of methods. The system achieved 77.7% average jackknifed accuracy for two states prediction based on a 25% relative solvent accessibility mode, with a Mathews' correlation coefficient of 0.548. The improved MLR secondary structure and relative solvent accessibility prediction server is available at http://spg.biosci.tsinghua.edu.cn/.

Algorithms↗
PubMed2005

Crystal structures of human HSP90alpha-complexed with dihydroxyphenylpyrazoles.

A series of dihydroxyphenylpyrazole compounds were identified as a unique class of reversible Hsp90 inhibitors. The crystal structures for two of the identified compounds complexed with the N-terminal ATP binding domain of human Hsp90alpha were determined. The dihydroxyphenyl ring of the compounds fits deeply into the adenine binding pocket with the C2 hydroxyl group forming a direct hydrogen bond with the side chain of Asp93. The pyrazole ring forms hydrogen bonds to the backbone carbonyl of Gly97, the hydroxyl group of Thr184 and to a water molecule, which is present in all of the published HSP90 structures. One of the identified compounds (G3130) demonstrated cellular activities (in Her-2 degradation and activation of Hsp70 promoter) consistent with the inhibition of cellular Hsp90 functions.

Cell Line↗
PubMed2005

Chemical fingerprint and metabolic fingerprint analysis of Danshen injection by HPLC-UV and HPLC-MS methods.

HPLC-UV and HPLC-MS techniques were used in fingerprint analysis of Danshen injection and its raw materials (roots and rhizoma of Salvia miltiorrhiza). HPLC profiles of Danshen injections from a Chinese pharmaceutical factory and their raw materials were established as their characteristic fingerprint and employed to assess their consistency and difference. To develop the representative fingerprint of Danshen injection, 10 batches of samples were analyzed under the same HPLC conditions. The results showed that 10 batches of Danshen injections had very similar HPLC fingerprints. To characterize the major constituents of Danshen injection for quality control, 11 major chromatographic peaks were characterized by their MS spectra and comparison with the reference standards. Through comparison of the HPLC profiles of Danshen injection with its raw material, it was found that they are greatly different, which indicated the changes of major constituents in the course of preparation procedure. In addition, the rat's plasma was analyzed by HPLC-MS technique after intravenous administration of Danshen injection at different time intervals to explore the in vivo metabolism of the major active constituents. Except for protocatechuic aldehyde, the major phenolic acids in Danshen injection appeared in rat's plasma after intravenous administration, but quantity of each phenolic acids was very different from that in Danshen injection. With the administration time prolonged danshensu and salvianolic acid B disappeared quickly, salvianolic D, lithospermic acid and salvianolic A slowly decreased and maintained relatively high concentration after 30 min of intravenous administration. This indicated that polyphenolic acids were significant for biological activity of Danshen injection. It might be concluded that chemical fingerprint combined with metabolic fingerprint is a useful means to control the quality and to clarify the possible mechanism of action of herbal products.

Animals↗
PubMed2005

Metabolic studies on the total phenolic acids from the roots of Salvia miltiorrhiza in rats.

Phenolic acids are the main active constituents of Salvia miltiorrhiza Bunge. The metabolism of total phenolic acids from the roots of Salvia miltiorrhiza in rats was investigated. A sample preparation method combining the solid-phase extraction with liquid-liquid extraction was established to separate metabolites from the biological matrix. HPLC-UV and HPLC-MS methods were employed to analyze the metabolites. Five metabolites (M1-M5) were identified by HPLC-MS analysis and comparison with those of the reference standards. The fi ve metabolites were characterized as danshensu (M1), caffeic acid (M2), ferulic acid (M3), isoferulic acid (M4) and methylized ferulic acid (M5), respectively. The possible metabolic pathway of the phenolic acids is proposed.

Animals↗
PubMed2005

Anti-SARS-CoV immunoglobulin G in healthcare workers, Guangzhou, China.

To determine the prevalence of inapparent infection with severe acute respiratory syndrome (SARS) among healthcare workers, we performed a serosurvey to test for immunoglobulin (Ig) G antibodies to the SARS coronavirus (SARS-CoV) among 1,147 healthcare workers in 3 hospitals that admitted SARS patients in mid-May 2003. Among them were 90 healthcare workers with SARS. As a reference group, 709 healthcare workers who worked in 2 hospitals that never admitted any SARS patients were similarly tested. The seroprevalence rate was 88.9% (80/90) for healthcare workers with SARS and 1.4% (15/1,057) for healthcare workers who were apparently healthy. The seroprevalence in the reference group was 0.4% (3/709). These findings suggest that inapparent infection is uncommon. Low level of immunity among unaffected healthcare workers reinforces the need for adequate personal protection and other infection control measures in hospitals to prevent future epidemics.

Adult↗
PubMed2005

[Genetic polymorphisms of nucleotide repair gene hMTH1 in southern Chinese Han population].

In order to study the genetic polymorphisms of nucleotide repair gene hMTH1 in southern Chinese Han population, the polymorphisms of the gene's promoter and its five exons among peripheral blood lymphocytes of 172 Chinese Han people were analyzed with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing. The sequences of the promoter and exon 1 of hMTH1 gene were conserved. A T to C polymorphism was detected at the 73th base in exon 2. The genotype frequencies of TT and TC were 93.02% and 6.98%, respectively. The allelic frequencies of T and C were 96.51% and 3.49%, respectively. A T to C polymorphism was detected at codon 45 in exon 3, which was first reported. The genotype frequencies of TT and TC were 95.35% and 4.65%, respectively. The allelic frequencies of T and C were 97.67% and 2.33%, respectively. A G to A polymorphism was detected at codon 83 in exon 4. The genotype frequencies of GG and GA were 89.53% and 10.47%, respectively. The allelic frequencies of G and A were 94.77% and 5.23%, respectively. A C to T polymorphism was detected at codon 119 in exon 5. The genotype frequencies of CC and CT were 95.93% and 4.07%, respectively. The allelic frequencies of C and T were 97.97% and 2.03%, respectively.

Asian People↗
PubMed2005

[Association of metabolic and DNA repair enzyme gene polymorphisms and DNA damage in coke-oven workers].

OBJECTIVE: To investigate the association of polymorphisms of metabolic and DNA repair enzyme genes and DNA damage in peripheral blood lymphocytes in coke-oven workers. METHODS: One hundred and forty-four coke-oven workers and 50 controls were recruited in this study. Urinary 1-hydroxypyrene (1-OHP) levels were measured as the internal dose of polycyclic aromatic hydrocarbons exposure. DNA damage was detected by alkaline comet assay, and the value of 1.74 was used as the cut-off value to determine whether the individual's DNA damage was positive. The genotypes of CYP1A1, CYP2E1, GSTP1, NQO1, mEH and XRCC1 were determined by PCR-based methods. With adjustment for urinary 1-OHP, age, sex, multiple analysis of covariance was used to study the association between genotypes and the ln-transformed olive TM and multiple logistic regression was used to calculate the adjusted OR and the 95% CI for the risk of DNA damage. RESULTS: In 144 coke-oven workers, with adjustment for urinary 1-OHP, coking history and sex, the olive TM was significantly higher with XRCC1 280His allele than those with Arg allele (5.6 vs. 2.8, P < 0.01). The subjects with XRCC1 280His allele also have significantly higher risk for DNA damage than subjects with Arg allele (adjusted OR = 2.66, 95% CI = 1.00-7.14, P = 0.05) and the subjects with GSTP1 104Val allele have higher risk for DNA damage than subjects with Ile allele (adjusted OR = 1.90, 95% CI = 0.94-3.85, P = 0.07). CONCLUSION: XRCC1 and GSTP1 polymorphisms might influence the susceptibility of DNA damage in occupational PAH-exposed coke-oven workers.

Adult↗
PubMed2005

[Correlations between BCG-PSN and tuberculin responses].

OBJECTIVE: To investigate the correlations between tuberculin responses and allergic rhinitis treated by BCG-PSN. METHOD: A total 60 patients with allergic rhinitis were randomly divided into BCG-PSN treated group and control group. All patients were given purified protein derivate (PPD), and PPD induration were recorded after 72 h, also the eosinophil cationic protein (ECP) and total IgE (TIgE) in serum were assayed with Pharmacia UniCAP System. RESULT: ECP and tIgE levels of patients treated by BCG-PSN were significantly lower than before treatment (P < 0.01). 37.5% patients who had negative reaction had induration after treatment using BCG-PSN. CONCLUSION: These results indicate that exposure BCG-PSN can correct the imbalance state of Th1 and Th2 cytokines and inhibit allergic airway inflammation and control allergic rhinitis.

Adolescent↗
PubMed2005

[Low concentration of hydroquinone-induced adaptive response in hPARP-1 protein normal and deficient cells].

OBJECTIVE: To investigate whether or not adaptive response of hPARP-1 protein normal and deficient cells is induced by low dose of hydroquinone (HQ), and to analyze the relationship between the adaptive response and micronuclei formation, and cell cycle alteration in human embryo lung fibroblasts (HLF), so as to elucidate the mechanism of adaptive response. METHODS: HLF, HLFC and HLFP cells pretreated with low concentration were retreated by high concentration of HQ. Cellular viability, the rate of micronuclei and abnormal nuclei, cell cycle and DNA strand break were determined. RESULTS: The tolerance to 80.0 micromol/L concentration of HQ was enhanced when HLF, HLFC and HLFP cells were pretreated with HQ from 0.001 - 0.050 micromol/L. There were varying degrees of micronuclei and abnormal nuclei in three cells pretreated with low concentration of HQ and then retreated with high concentration of HQ; the cell numbers of G1, G2, S phase in cell cycle were obviously different. When compared with only high attack dose, the micronuclei rate and abnormal nuclei rate of HLF, HLFC and HLFP decreased by pretreatment with HQ at high concentration (P < 0.05), meanwhile increased by pretreatment with HQ at low concentration (P < 0.05). HLF, HLFC and HLFP showed blockage in G2 phase when pretreated with HQ at 0 approximately 0.05 micromol/L, but HLFP showed blockage in G1 phase, and in S phase at 1.0 and 2.0 micromol/L. CONCLUSION: The level of adaptive response of hPARP-1 protein deficient cells was lower than normal cell, suggesting that hPARP-1 protein may play an important role in the adaptive response of cells, which may be related with the regulation of cell cycle.

Cell Cycle↗
PubMed2005

[Construction of hPARP1-deficient cell strain by RNA interference].

OBJECTIVE: To construct hPARP1-deficient cell strain which can be used in studying the functions and action mechanisms of hPARP1 gene. METHODS: 16-HBEs were transfected with two kinds of eukaryotic expression plasmids of hPARP1 gene short hairpin RNA to construct hPARP1-deficient cells (named as "16-HBEP1 and 16-HBEP2") and a negative control plasmids (named as 16-HBEN). The protein expression levels of hPARP1 gene in 16-HBE, 16-HBEP1 16-HBEP2 and 16-HBEN were detected by the western blotting to estimate the effects of RNA interference. RESULTS: The construction of hPARP1-deficient cell strain was successful and the protein expression level of hPARP1 gene in the 16-HBEP1 and 16-HBEP2 were decreased 84.3% and 63.7% respectively as compared with that in 16-HBE. CONCLUSION: The successes in constructing hPARP1-deficient strain offered an effective cell strain for studying the function of hPARP1 gene.

Bronchi↗
PubMed2004

Identification of novel potent bicyclic peptide deformylase inhibitors.

Screening of our compound collection using Staphylococcus aureus Ni-Peptide deformylase (PDF) afforded a very potent PDF inhibitor with an IC(50) in the low nanomolar range but with poor antibacterial activity (MIC). Three-dimensional structural information obtained from Pseudomonas aeruginosa Ni-PDF complexed with the inhibitor suggested the synthesis of a variety of analogues that would maintain high binding affinity while attempting to improve antibacterial activity. Many of the compounds synthesized proved to be excellent PDF-Ni inhibitors and some showed increased antibacterial activity in selected strains.

Amidohydrolases↗
PubMed2004

Synthesis and biological evaluations of novel benzimidazoles as potential antibacterial agents.

A series of novel benzimidazole derivatives were synthesized via parallel solution-phase chemistry. Many of these compounds were found to inhibit the growth of Staphylococcus aureus and Escherichia coli. Several analogues exhibited low micromolar minimal inhibitory concentrations (MIC) against both Gram-positive and Gram-negative bacteria of clinical relevance and could serve as leads for further optimizations for antibacterial research.

Anti-Bacterial Agents↗