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Hong Lu

Publications and source records attributed to Hong Lu.

At least 91 records · Page 5Linked to original sources
PubMed2004

Global mapping of the yeast genetic interaction network.

A genetic interaction network containing approximately 1000 genes and approximately 4000 interactions was mapped by crossing mutations in 132 different query genes into a set of approximately 4700 viable gene yeast deletion mutants and scoring the double mutant progeny for fitness defects. Network connectivity was predictive of function because interactions often occurred among functionally related genes, and similar patterns of interactions tended to identify components of the same pathway. The genetic network exhibited dense local neighborhoods; therefore, the position of a gene on a partially mapped network is predictive of other genetic interactions. Because digenic interactions are common in yeast, similar networks may underlie the complex genetics associated with inherited phenotypes in other organisms.

Amino Acid Sequence↗
PubMed2004

The Helicobacter pylori restriction endonuclease-replacing gene, hrgA, and clinical outcome: comparison of East Asia and Western countries.

It has been suggested that the putative Helicobacter pylori virulence factor hrgA is the first disease-specific marker for an H. pylori-related disease, (i.e., development of gastric cancer in East Asia). Our aim was to test the hypothesis that the presence of hrgA has disease specificity. We examined 458 H. pylori isolates including 289 from East Asia and 169 from Western countries whose cagA and vacA genotypes had previously been characterized. hrgA/hpyIIIR status and iceA genotypes were determined by polymerase chain reaction using DNA expanded from a single colony. hrgA was present in 29% of gastric cancers, 29% of ulcers, and 31% of gastritis cases among H. pylori from East Asia (P > 0.9). Overall, there was no significant relationship between the presence of the hrgA gene and disease presentation (cancer, ulcer, or neither) or between its presence and the cag pathogenicity island, vacA s1 , babA2, and oipA, "on" genotypes. The prevalence of the hrgA gene was significantly lower in H. pylori from East Asia (29%) vs. those from the West (49%) (P < 0.001). The prevalence of the hrgA gene was not related to clinical outcome or to other important putative virulence factors.

Age Distribution↗
PubMed2004

Role of interferon-stimulated responsive element-like element in interleukin-8 promoter in Helicobacter pylori infection.

BACKGROUND & AIMS: Gastric mucosal interleukin (IL)-8 levels are related to the presence of both the cag pathogenicity island (PAI) and OipA. We investigated the regions of the IL-8 promoter and the upstream signaling involved in IL-8 gene transcription. METHODS: We cocultured parental Helicobacter pylori and isogenic oipA, hopZ, or cagE gene knockout mutants with gastric cancer cells. The regulatory sites in the IL-8 promoter were examined by luciferase reporter gene assay, electrophoretic mobility shift assays, and immunoblot analyses. Phosphorylated signal transducers and activators of transcription 1 (STAT1) levels in the antral gastric mucosa were measured by enzyme-linked immunosorbent assay. RESULTS: Maximal H. pylori -induced IL-8 gene transcription required the presence of the interferon-stimulated responsive element (ISRE)-like element, nuclear factor (NF)-kappa B and activator protein (AP)-1 binding sites. In vitro studies showed that OipA and the cag PAI were involved in inducing interferon regulatory factor (IRF)-1 to bind and activate the ISRE-like element and that the cag PAI, but not OipA, was involved in activating AP-1 and NF-kappa B. Both in vitro and in vivo studies showed that OipA, but not the cag PAI, was involved in STAT1 phosphorylation, as upstream signaling of IRF-1. CONCLUSIONS: OipA and the cag PAI are both necessary for full activation of the IL-8 promoter but act via different pathways that diverge upstream of IRF-1 where only OipA is involved in the STAT1-IRF1-ISRE pathway. The mucosal inflammatory response to H. pylori infection is complex and involves different pathways converging on the IL-8 promoter.

Antigens, Bacterial↗
PubMed2004

False negative urea breath tests with H2-receptor antagonists: interactions between Helicobacter pylori density and pH.

BACKGROUND: We studied the effects of famotidine, sodium bicarbonate, and citric acid on the 13C-urea breath test (UBT). METHODS: Helicobacter pylori-infected volunteers received a UBT, 40 mg of famotidine at bedtime, and a second UBT (pudding test meal, 648 mg NaHCO3 tablet then 125 mg of urea in 200 ml of water containing 650 mg of NaHCO3). Experiment 2 consisted of four UBTs. Two were standard citric acid UBTs with 75 mg of urea and 2 g citric acid and two were sequential bicarbonate-citric acid UBTs. Sequential UBTs consisted of administration of a 648 mg bicarbonate tablet with 50 g of Polycose in 200 ml of water. Five minutes later, 125 mg of 13C-urea was given in 75 ml of water containing 650 mg of NaHCO3. Breath samples were collected after 15 minutes. Then, to acutely acidify the stomach, 4 g of citric acid was given in 200 ml of water. A second breath sample was collected 15 minutes after the citric acid. The standard UBTs were done before and after 6 days of famotidine (40 mg b.i.d.). Sequential UBTs were done after 1 and 6 days of famotidine therapy. Gastric biopsies for histology, culture, and mucosal cytokines were assessed before and after 6 days of famotidine. RESULTS: Eighteen subjects participated, 10 in each experiment; seven had endoscopy with biopsy. Famotidine/ bicarbonate resulted an approximately 50% fall in UBT values (p = .021) with 10% becoming negative. The gastric pH increased from 5.1 +/- 0.5 to 6.7 +/- 0.2 (p = .03) although no pH value predicted the occurrence of false negative results. Under famotidine acid suppression, NaHCO3 reduced the delta over baseline (DOB) by 63% (p = .021). This was reversed with citric acid. Histology showed a H2-receptor antagonist-associated increase in the depth of gastric corpus inflammation. CONCLUSIONS: H2-receptor antagonists differ from proton pump inhibitors as high intragastric pH may cause a reduction in urease activity, unrelated to a reduced bacterial load and reversed by citric acid.

Adolescent↗
PubMed2004

N-substituted pyrrole derivatives as novel human immunodeficiency virus type 1 entry inhibitors that interfere with the gp41 six-helix bundle formation and block virus fusion.

A recently approved peptidic human immunodeficiency virus type 1 (HIV-1) fusion inhibitor, T-20 (Fuzeon; Trimeris Inc.), has shown significant promise in clinical application for treating HIV-1-infected individuals who have failed to respond to the currently available antiretroviral drugs. However, T-20 must be injected twice daily and is too expensive. Therefore, it is essential to develop orally available small molecule HIV-1 fusion inhibitors. By screening a chemical library consisting of "drug-like" compounds, we identified two N-substituted pyrroles, designated NB-2 and NB-64, that inhibited HIV-1 replication at a low micromolar range. The absence of the COOH group in NB-2 and NB-64 resulted in a loss of anti-HIV-1 activity, suggesting that this acid group plays an important role in mediating the antiviral activity. NB-2 and NB-64 inhibited HIV-1 fusion and entry by interfering with the gp41 six-helix bundle formation and disrupting the alpha-helical conformation. They blocked a d-peptide binding to the hydrophobic pocket on surface of the gp41 internal trimeric coiled-coil domain. Computer-aided molecular docking analysis has shown that they fit inside the hydrophobic pocket and that their COOH group interacts with a positively charged residue (K574) around the pocket to form a salt bridge. These results suggest that NB-2 and NB-64 may bind to the gp41 hydrophobic pocket through hydrophobic and ionic interactions and block the formation of the fusion-active gp41 core, thereby inhibiting HIV-1-mediated membrane fusion and virus entry. Therefore, NB-2 and NB-64 can be used as lead compounds toward designing and developing more potent small molecule HIV-1 fusion inhibitors targeting gp41.

CD4 Antigens↗
PubMed2004

Delivery of tea polyphenols to the oral cavity by green tea leaves and black tea extract.

Catechins and theaflavins, polyphenolic compounds derived from tea (Camellia sinensis, fam. Theaceae), have been reported to have a wide range of biological activities including prevention of tooth decay and oral cancer. The present study was undertaken to determine the usefulness of green tea leaves and black tea extract for the delivery of catechins and theaflavins to the oral cavity. After holding either green tea leaves (2 g) or brewed black tea (2 g of black tea leaves in 100 ml) in the mouth for 2-5 min and thoroughly rinsing the mouth, high concentrations of catechins (C(max) = 131.0-2.2 micro M) and theaflavins (C(max) = 1.8-0.6 micro M) were observed in saliva in the 1st hour. Whereas there was significant interindividual variation in the peak levels of catechins and theaflavins, the overall kinetic profile was similar, with t(1/2) = 25-44 min and 49-76 min for catechins and theaflavins, respectively (average coefficient of variation in t(1/2) was 23.4%). In addition to the parent catechin and theaflavin peaks, five unidentified peaks were also observed in saliva after black tea treatment. Hydrolysis of theaflavin gallates, apparently by salivary esterases, was observed in vitro and in vivo. These results indicate that tea leaves can be used as a convenient, slow-release source of catechins and theaflavins and provide information for the possible use of tea in the prevention of oral cancer and dental caries.

Adult↗
PubMed2004

Multiplexed RT- PCR for high throughput screening applications.

To increase efficiency of high throughput gene expression profiling, we established a new TaqMan RT-PCR (real-time reverse transcriptase-polymerase chain reaction with internal probes for the quantification of PCR products) method for quantitative mRNA expression analysis. In this procedure, we utilized poly-A mRNA capture plates and validated a multiplexed single tube RT-PCR assay for cell culture applications, including compound testing via gene induction measurement. In the described procedure, all steps including RNA extraction, RT and PCR are performed in the same tube, thus significantly enhancing throughput of this method. Optimization of conditions, including the number of cells necessary for detection of mRNA signal was performed. With a relatively abundant message such as GAPDH, we saw a linear response for all of the concentrations tested, from 10,000 cells to 10 cells. We have also demonstrated multiplexing of different targets within the PCR reactions. In these experiments, we combined VIC-labeled probes for GAPDH with several FAM-labeled probes obtained from Assays On Demand (Applied Biosystems). In the reported experiments, multiplexing did not affect the efficiency of RT-PCR. We also demonstrated the utility of this technology for compound screening applications. The described technology also has the potential to accelerate studies on target and biomarker identification and toxicity assessment in ADMET (absorption, distribution, metabolism, elimination, and toxicity) testing.

Cell Count↗
PubMed2004

Gene expression analysis for high throughput screening applications.

To meet growing needs for high throughput gene expression profiling, we established a new automated high throughput TaqMan RT-PCR method for quantitative mRNA expression analysis. In this method, the Allegro( trade mark ) (Zymark) system conducts all sample tracking and liquid handling steps, and ABI PRISM 7900 HT (Applied Biosystems) is used to conduct real-time determination of the C(t) value when amplification of PCR products is first detected and accumulation of inhibitory PCR products is unlikely to occur. The ABI PRISM 7900 HT Sequence Detection System features a real-time PCR instrument with 384-well-plate compatibility and robotic loading, and continuous wavelength detection, which enables the use of multiple fluorophores in a single reaction. The Allegro System offers an assembly line approach with a modular design that allows reconfiguration of the components to accommodate variations in the assay flow. In the present study, we have established and validated a new automated High Throughput (HT) TaqMan RT-PCR- based method for quantitative mRNA expression analysis. The data demonstrate that HT-Taqman PCR is a powerful tool that can be used for measuring low concentrations of mRNA, and is highly accurate, reproducible, and amenable to high throughput analysis. Results suggest that HT-TaqMan is a reliable method for the quantification of low-expression genes and a powerful tool with HT capability for target identification/validation, structure-activity relationship (SAR) study, compound selection for efficacy studies, and biomarker identification in drug discovery and development.

Drug Design↗
PubMed2004

[A study on the effects of cells and scaffolds tissue engineering on the periodontal regeneration].

OBJECTIVE: To observe the effects of cells and scaffolds tissue engineering on the periodontal regeneration, and to evaluate the feasibility of nano-Hap-collagen (nHAC) as the scaffold material for periodontal tissue engineering. METHODS: Dog autogenous periodontal ligament cells (PDLCs) cultured in vitro were collected and seeded on the three-dimensional framework of nHAC. The cell growth in the scaffolds was observed by scanning electron microscope. And then the PDLCs-nHAC composites were transplanted into man-made periodontal defects, and the groups filled with nothing or filled only with nHAC were the controls. The dogs were sacrificed after 8 weeks and the periodontal regeneration was observed histologically. RESULTS: Scanning electron microscope showed the porous structure of nHAC and the eugonic growth of cells in the nHAC scaffolds. The histological observation showed that the PDLCs-nHAC groups exhibited more new bone, new periodontal ligament and new cementum occupying the majority of the defects than the control groups, and the epitheliums were not observed. CONCLUSIONS: Periodontal regeneration could be enhanced by the cells and scaffolds tissue engineering, and the PDLCs and nHAC could be used as the seed cell and the scaffold material for periodontal tissue engineering.

Animals↗
PubMed2004

[Effect of combination of Ginkgo leaf extract and deferoxamine in preventing and treating ototoxicity of cisplatin].

OBJECTIVE: To observe the effect of combined use of jinnaduo (an injection made by extract of Ginkgo leaf, EGb) and Deferoxamine (DFO, a chelating agent) in antagonizing the ototoxicity of cisplatin (CDDP). METHODS: Guinea pigs were randomly divided into the CDDP group, the EGb group, the DFO group, the combined treated group (EGb + DFO) and the control group. Changes of auditory brain-stem response (ABR), serum superoxide dismutase (SOD) activity and malondialdehyde (MDA) content, as well as light and scanning electronic microscopic (SEM) figures were observed before and after treatment. RESULTS: The threshold of ABR was significantly higher in the CDDP group than that in the other groups (P<0.01), but was insignificantly different among the latter groups (P>0.05). Serum SOD activity was lower and MDA content was higher in the CDDP group than those in the control group (P<0.01), but in comparison of the two parameters between control and other groups, the difference was insignificant (P>0.05). SEM examination on cochlea showed that the damage of hair cells was milder in the DFO group and the combined treated group than that in the CDDP group, which was slightly milder in the EGb group than that in the CDDP group. CONCLUSION: Combined use of EGb and DFO could effectively reduce the ototoxicity of CDDP, its effect is better than using EGb singly, and similar to that of using DFO alone. The combination could also prevent the side-effect of CDDP in bone marrow inhibition. The Fe ion participated free radical response could be one of the mechanisms of CDDP in damaging hearing.

Animals↗
PubMed2004

[Rapid pathogens diagnosis of infected keratitis and endophthalmitis using two steps polymerase chain reaction].

OBJECTIVE: To establish a rapid diagnosis technique of the pathogens of infected keratitis and endophthalmitis. METHODS: Fifty-one corneal scraping, tear and 16 vitreous specimens were obtained from 67 cases of infected keratitis and endophthalmitis. Multiplex polymerase chain reaction (MPCR) was performed to differentiate the genes of bacteria, fungi and HSV using their own universal primers. Special-primers PCR were carried out for MPCR positive specimens to detect the genes of common bacteria and fungi respectively. The results were compared with microbe culture and clinical diagnosis. RESULTS: In 67 clinical samples, 52 (77.6%) were positive at least one kind of pathogen by MPCR (two positive pathogens were 8 cases). SPCR revealed that 7 bacteria (25.0%) out of 28 bacteria positive specimens were Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa. Eight fungi (53.3%)of 15 fungi positive specimens was Candida, Aspergillus, Fusarium. The culture positive rates were 31.3% (21 cases), among them 1 case was found positive for two pathogens. MPCR positive rate was statistically higher than the rate that in culture (chi(2) = 13.50, P < 0.005). The kinds of bacteria and fungi of SPCR positive were as the same as bacteria and fungi of culture positive. Consistency of clinical diagnosis and experimental evidences of infected keratitis was 54.8%. The time for microbe culture needs 72 to 96 hours, but MPCR and SPCR needs 8 hours. CONCLUSION: Two steps PCR is rapid, sensitive method to detect the pathogens of infected keratitis and endophthalmitis.

Adolescent↗
PubMed2003

Tea polyphenol (-)-epigallocatechin-3-gallate inhibits DNA methyltransferase and reactivates methylation-silenced genes in cancer cell lines.

Hypermethylation of CpG islands in the promoter regions is an important mechanism to silence the expression of many important genes in cancer. The hypermethylation status is passed to the daughter cells through the methylation of the newly synthesized DNA strand by 5-cytosine DNA methyltransferase (DNMT). We report herein that (-)-epigallocatechin-3-gallate (EGCG), the major polyphenol from green tea, can inhibit DNMT activity and reactivate methylation-silenced genes in cancer cells. With nuclear extracts as the enzyme source and polydeoxyinosine-deoxycytosine as the substrate, EGCG dose-dependently inhibited DNMT activity, showing competitive inhibition with a K(i) of 6.89 microM. Studies with structural analogues of EGCG suggest the importance of D and B ring structures in the inhibitory activity. Molecular modeling studies also support this conclusion, and suggest that EGCG can form hydrogen bonds with Pro(1223), Glu(1265), Cys(1225), Ser(1229), and Arg(1309) in the catalytic pocket of DNMT. Treatment of human esophageal cancer KYSE 510 cells with 5-50 microM of EGCG for 12-144 h caused a concentration- and time-dependent reversal of hypermethylation of p16(INK4a), retinoic acid receptor beta (RARbeta), O(6)-methylguanine methyltransferase (MGMT), and human mutL homologue 1 (hMLH1) genes as determined by the appearance of the unmethylation-specific bands in PCR. This was accompanied by the expression of mRNA of these genes as determined by reverse transcription-PCR. The re-expression of RARbeta and hMLH1 proteins by EGCG was demonstrated by Western blot. Reactivation of some methylation-silenced genes by EGCG was also demonstrated in human colon cancer HT-29 cells, esophageal cancer KYSE 150 cells, and prostate cancer PC3 cells. The results demonstrate for the first time the inhibition of DNA methylation by a commonly consumed dietary constituent and suggest the potential use of EGCG for the prevention or reversal of related gene-silencing in the prevention of carcinogenesis.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Construction of a genetically engineered microorganism for CO2 fixation using a Rhodopseudomonas/Escherichia coli shuttle vector.

The CO2 fixation ability of Rhodopseudomonas palustris DH was enhanced by introducing the recombinant plasmid pMG-CBBM containing the form II ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) gene (cbbM) isolated from Rps. palustris NO. 7. Sequencing of a 3.0-kb PstI fragment containing the cbbM gene revealed an open reading frame encoding 461 amino acids, homologous to known cbbM genes, with a ribosome binding site upstream of cbbM and a terminator downstream of cbbM, without promoter. pMG-CBBM, a Rhodopseudomonas/Escherichia coli shuttle expression plasmid, was derived from the Rhodopseudomonas/E. coli shuttle cloning vector pMG105, by inserting the promoter of the pckA gene and the cbbM gene into its multiple cloning site. Plasmid pMG-CBBM was transformed into Rps. palustris DH by electroporation, and was stably maintained when transformants were grown either photoheterotrophically or photolithoautotrophically in the absence of antibiotics. This is the first report of an expression plasmid containing a Rps. palustris-specific promoter that allows stable expression of a foreign gene in the absence of antibiotic selection.

Amino Acid Sequence↗
PubMed2003

The apoptosis-associated protein BNIPL interacts with two cell proliferation-related proteins, MIF and GFER.

Bcl-2/adenovirus E1B 19 kDa interacting protein 2-like, BNIP-2-like (BNIPL) is a recently cloned and characterized apoptosis-associated protein that shares 72% homology with BNIP-2. It is highly expressed in human placenta and lung. A yeast two-hybrid system was used to obtain two BNIPL-interacting proteins, MIF (macrophage migration inhibitory factor) and GFER (growth factor erv1 (Saccharomyces cerevisiae)-like). The interactions were confirmed by glutathione S-transferase pull-down assay in vitro and co-immunoprecipitation assay in vivo. Colony formation assay and cell proliferation test suggest that overexpression of BNIPL could inhibit the growth of BEL-7402 cells. These findings suggest that BNIPL may physically bind to cell proliferation-related proteins, MIF and GFER.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Haplotype analyses of cholesteryl ester transfer protein gene promoter: a clue to an unsolved mystery of TaqIB polymorphism.

Cholesteryl ester transfer protein (CETP) mediates the transfer of cholesteryl esters from HDL to triglyceride-rich lipoproteins. TaqIB polymorphism (B2 allele) identified in intron 1 is associated with lower plasma CETP concentrations and higher HDL cholesterol levels and may play an antiatherogenic role in humans. However, its molecular mechanism remains unclear. To evaluate the association between the promoter polymorphisms and CETP/HDL cholesterol levels, ten novel and three previously reported polymorphisms located within 3.3 kb of the CETP gene promoter were investigated in a sample of 357 elderly Japanese men. All the promoter polymorphisms were in linkage disequilibrium with each other and with TaqIB. The -2505A allele, the "S" allele of the [gaaa](n) repeat ("S" denotes [gaaa](n)=329 bp and longer, "L" denotes >329 bp) and TaqIB2 allele were significantly associated with both lower plasma CETP concentrations and higher HDL cholesterol levels whereas -971G/A and -629A/C were significantly associated with CETP concentrations but not with HDL-C levels. The 12-polymorphism haplotypes consisting of -2804, -2505, [gaaa](n), -1930, -1674, -1129, -1046, -971, -875, -827, -629, and TaqIB were analyzed. These 12 polymorphisms generated eight main haplotypes, accounting for 86% of the observed haplotypes. The G/A/S/T/T/C/T/A/C/C/A/B2 haplotype was significantly associated with lower CETP concentrations (2.0+/-0.6 micro g/ml) and higher HDL cholesterol levels (55.1+/-12.7 mg/dl) than the other seven main haplotypes. The 5- and 3-polymorphism haplotype analyses consisting of -2505 and the [gaaa](n) repeat indicated the -2505C/A polymorphism might explain the variation in the CETP concentrations best, and the [gaaa](n) repeat and/or the -2505C/A polymorphism may independently determine the variation in HDL cholesterol levels, whereas the -629A/C and TaqIB polymorphisms were not instrumental in determining CETP concentrations as well as HDL cholesterol levels, although the latter has been frequently examined in many association studies.

Aged↗
PubMed2003

Signal-to-noise ratio effects in quantitative cerebral perfusion using dynamic susceptibility contrast agents.

Theoretical and simulation evidence is presented in support of the idea that the optimal manner of determining blood flow from MR perfusion studies is not necessarily obtained by setting experimental conditions to maximize either the arterial input or the measured tissue concentration level for a particular echo time (TE). The noise power in the contrast concentration curve is associated with its peak because of the nonlinear relationship between the contrast concentration and MR signal intensity curves. The optimum signal-to-noise ratio (SNR), SNR(C), for a particular contrast concentration curve can be obtained when the experimental concentration level and TE are adjusted to produce an MR intensity curve whose signal loss is 63% of the precontrast MR signal intensity. It is demonstrated that the stability of the singular valued decomposition (SVD) deconvolution approach to determine blood flow parameters is increased when the tissue curve maximum signal loss is in the range of 40-80%. The accuracy and stability of the SVD-determined blood flow parameters are affected by deviations from these optimum conditions in a manner that depends on the mean transit time (MTT) associated with the residue function. It is recommended that the experimental TE value be set so that neither the tissue nor the arterial curves are placed a region of rapidly deteriorating SNR(C).

Blood Flow Velocity↗
PubMed2003

Automatic quantitation of HIV-1 mediated cell-to-cell fusion with a digital image analysis system (DIAS): application for rapid screening of HIV-1 fusion inhibitors.

Human immunodeficiency viruses type 1 (HIV-1) mediated cell-to-cell fusion plays an important role in HIV-1 spread from infected cells to uninfected cells and in HIV-1 cytopathogenesis. In the present study, we developed a convenient cell fusion assay using a computer-controlled digital image analysis system (DIAS) for automatic quantitation. Compared with a manual quantitative method, DIAS automatic method is less laborious, and more rapid. Furthermore, it is more objective and less dependent on the researchers' experience. This method has great potential to be developed further as a high-throughput screening assay for rapid screening of HIV-1 fusion inhibitors, for evaluating the activity of HIV-1 entry inhibitors and for studying the mechanism of action of anti-HIV-1 agents.

Cell Fusion↗