Biomedical subjects

Hong Cai

Publications and source records attributed to Hong Cai.

At least 37 records · Page 2Linked to original sources

PubMed2005

The rice bran constituent tricin potently inhibits cyclooxygenase enzymes and interferes with intestinal carcinogenesis in ApcMin mice.

While brown rice is a staple dietary constituent in Asia, rice consumed in the Western world is generally white, obtained from brown rice by removal of the bran. Rice bran contains the flavone tricin, which has been shown to inhibit colon cancer cell growth. We tested the hypothesis that tricin interferes with adenoma formation in the Apc(Min) mouse. Mice received tricin (0.2%) in their American Institute of Nutrition 93G diet throughout their postweaning life span (4-18 weeks). Consumption of tricin reduced numbers of intestinal adenomas by 33% (P < 0.05) compared with mice on control diet. We explored whether tricin may exert its effect via inhibition of cyclooxygenase (COX) enzymes. Its effect on COX activity was assessed in purified enzyme preparations in vitro and its ability to reduce prostaglandin E(2) (PGE(2)) levels in human colon-derived human colon epithelial cell (HCEC) and HCA-7 cells in vitro and in Apc(Min) mice in vivo. Tricin inhibited activity of purified COX-1 and COX-2 enzyme preparations with IC(50) values of approximately 1 micromol/L. At 5 micromol/L, it reduced PGE(2) production in HCEC or HCA-7 cells by 36% (P < 0.01) and 35% (P < 0.05), respectively. COX-2 expression was reduced by tricin weakly in HCEC and unaffected in HCA-7 cells. PGE(2) levels in the small intestinal mucosa and blood of Apc(Min) mice that had received tricin were reduced by 34% (P < 0.01) and 40% (P < 0.05), respectively, compared with control mice. The results suggest that tricin should be further evaluated as a putative colorectal cancer chemopreventive agent.

Adenoma↗

PubMed2005

Importance of C-reactive protein in regulating monocyte tissue factor expression in patients with inflammatory rheumatic diseases.

OBJECTIVE: To determine the relationship between plasma C-reactive protein (CRP) concentrations and monocyte tissue factor (TF) expression induced in vitro by combinations of CRP, ss2-glycoprotein I (ss2-GPI), and lipopolysaccharide (LPS). METHODS: Peripheral blood mononuclear cells (PBMC) from 26 healthy individuals and 31 patients with inflammatory rheumatic diseases (IRD) were cultured with combinations of CRP, purified or recombinant ss2-GPI, and LPS and monocyte TF procoagulant activity, TF antigen, and TF mRNA were measured. Results were examined against plasma CRP levels. RESULTS: Monocytes from patients with IRD expressed significantly more TF when stimulated with CRP compared to normal monocytes (p = 0.002). An incremental positive correlation was observed between plasma CRP levels and TF induced by CRP or ss2-GPI. Significantly more TF was induced with CRP combined with ss2-GPI, compared to ss2-GPI alone, either with costimulation or CRP priming. Conversely, when combined with LPS, ss2-GPI suppressed TF induction in a dose-dependent manner on normal PBMC but not on PBMC from patients with IRD. The loss of suppression correlated strongly with plasma CRP levels. CONCLUSION: This study shows a remarkably consistent effect of CRP on monocyte TF expression. Systemic inflammation associated with elevated plasma CRP conferred a phenotype on PBMC, whereby incremental priming with respect to TF expression (induced by CRP itself or ss2-GPI) was apparent, and ss2-GPI-mediated inhibition of TF expression induced by LPS was incrementally lost. CRP regulation of monocyte TF could contribute to the higher than expected atherosclerotic vascular disease seen in patients with IRD.

Adult↗

PubMed2005

[Establishment and application of real-time fluorescence polymerase chain reaction based on the TaqMan probes for detection of Yersinia pestis].

OBJECTIVE: Establishing and developing methods for quick, special and of Yersinia pestis (Y. pestis). METHODS: Using real-time fluorescence polymerase chain reaction (PCR) based on TaqMan technology with UDG anti-contamination systems and ROX reference dye, we established a method to detect Y. pestis. Probes and primers from pla, caf1, hms and inv gene were designed. An internal positive control was added to the reaction mixture in order to detect the presence of PCR inhibitors that were often found in biological samples. Sensitivity was evaluated by serial dilution of colons, internal template and Y. pestis strains while specificity was confirmed by amplifying real DNAs from bacteria, the representative Y. pestis strains and blind assay. RESULTS: The methods used could provide quick, special and sensitive detection of Y. pestis, with sensitivities of pla, f1, hms as 10, 1 and 1 copie(s) respectively. CONCLUSION: The newly developed technologies seemed to be well suited to identify the Y. pestis in case of emergency, bio-terrorist attack and surveillance of the epidemics.

Animals↗

PubMed2004

Exonuclease I hydrolyzes DNA with a distribution of rates.

We report heterogeneity in the time necessary for Exonuclease I to hydrolyze identical DNA fragments. A real-time fluorescence method measured the time required by molecules of Exonuclease I to hydrolyze single-stranded DNA that was synthesized to have two fluorescently labeled nucleotides. One fluorescently labeled nucleotide was located near the 3' end of the DNA and the other near the 5' end. Heterogeneity in the hydrolysis rate of the exonuclease population was inferred from the distribution of times necessary to cleave these DNA fragments. In particular, we found simple first-order kinetics, using a single hydrolysis rate, did not result in a good fit to the data. Better fits to the data were obtained if one assumed a distribution of hydrolysis rates for the exonuclease population. Under our experimental conditions, this broad distribution of rates was centered near 100 nt/s.

DNA↗

PubMed2004

Virulence signatures: microarray-based approaches to discovery and analysis.

Rapid, accurate, and sensitive detection of biothreat agents requires a broad-spectrum assay capable of discriminating between closely related microbial or viral pathogens. Moreover, in cases where a biological agent release has been identified, forensic analysis demands detailed genetic signature data for accurate strain identification and attribution. To date, nucleic acid sequences have provided the most robust and phylogentically illuminating signature information. Nucleic acid signature sequences are not often linked to genomic or extrachromosomal determinants of virulence, a link that would further facilitate discrimination between pathogens and closely related species. Inextricably coupling genetic determinants of virulence with highly informative nucleic acid signatures would provide a robust means of identifying human, livestock, and agricultural pathogens. By means of example, we present here an overview of two general applications of microarray-based methods for: (1) the identification of candidate virulence factors; and (2) the analysis of genetic polymorphisms that are coupled to Bacillus anthracis virulence factors using an accurate, low cost solid-phase mini-sequencing assay. We show that microarray-based analysis of gene expression can identify potential virulence associated genes for use as candidate signature targets, and, further, that microarray-based single nucleotide polymorphism assays provide a robust platform for the detection and identification of signature sequences in a manner independent of the genetic background in which the signature is embedded. We discuss the strategy as a general approach or pipeline for the discovery of virulence-linked nucleic acid signatures for biothreat agents.

Bacillus anthracis↗

PubMed2004

[Discussion for clinical treatment in early stage of colorectal carcinoma with the invasion limited in the layer of muscularis mucosae].

OBJECTIVE: To emphasis the importance of recognizing and treating the early colorectal carcinoma with the invasion limited in the layer of muscularis mucosae, and discuss several questions in using the WHO's new diagnostic standards of the prestage of tumors of digestive system. METHODS: A retrospective review was made of 30 patients with invasive carcinoma limited in the layer of muscularis mucosae. All of the patients were treated between July 1986 and July 1999 in Shanghai Cancer Hospital. RESULTS: Among the 30 cases, there were 19 men and 11 women from 20 to 80 years dd (mean, 57.0). The tumor diameter was ranged from 0.8 cm to 8.0 cm (mean, 2.9 cm). 12 patients were given polypectomy while 18 patients were given radical resection. Among the patients given polypectomy, one got recurrence 3 years later, one had the metastasis of lungs 50 months later and had been dead already. Among the patients given radical resection, one had metastasis of lymph nodes peripheral to the tumor, one also had the metastasis of lungs 68 months later but is still alive now, and one had metastasis of lymph nodes in the right upper part of neck 15 months later and then was lost to follow-up. CONCLUSIONS: The patients with early colorectal carcinoma with the invasion limited in the layer of muscularis mucosae could have metastasis of lymph nodes, get local recurrence after polypectomy and even have blood metastasis. Therefore great attention must be paid. Clinicians should be careful to chosen polypectomy. Meanwhile, in order to provide more information of the correct treatment, it will be better if the pathologists could give the original diagnosis at the same time when they use the WHO's new diagnostic standards of the prestage of tumors of digestive system in diagnosing the early invasive carcinoma limited in the layer of muscularis mucosae, for the concept of high-grade intraepithelial neoplasia will be used instead of it, and whether or not it is a really benign tumor, much more clinical research must be done later.

Adult↗

PubMed2004

[Realization of clinical diagnoses and treatment for dermatofibrosarcoma protuberans].

OBJECTIVE: To emphasize the importance of correct and standardized surgical treatment on dermatofibrosarcoma protuberans (DFSP), and discuss the suitable synthesized therapy on it. METHODS: 163 cases of DFSP, which were treated between January 1985 and September 2002,were submitted to a retrospective study. RESULTS: Among the 163 cases, 150 (92.0%) were treated with local excision as benign tumors before accepted to Cancer Hospital, Fudan University. 69 cases (46.0%) were approved by pathological examination to have tumor remnants after they were treated with wide excision, and 49 (71.0%) of them couldn't be found to have any tumor remnants by physical examination or B-ultrasonic examination before that operation. It was easy for the tumor to recur after excision, especially the local excision. The recurrent rate after it was 45.1%, which was much higher than the one after wide excision (5.6%). Among the 142 cases which wide excision were performed, 99 ones had excision margins >/= 3 cm and 5 of them (5.1%) developed local recurrence while 36 ones had excision margins 1 approximately 2 cm and 3 of them (8.3%) developed local failure. 46 cases (32.4%) were given skin graft, 11 cases were given flap, and 1 case had dacron mending in skin defection area. The main complications after these operations were necrosis of the skin flap (20 cases) and infection of the wound (6 cases). They could all be cured in 2 months. 17 cases were given complimentary radiotherapy with the dose range from 3275 cGy to 7000 cGy because of their recurrences for times or positive resection margins after wide excision. Only one case had wet molting after radiotherapy and 2 developed local recurrence. Among all the 163 cases, only 2 (1.2%) were dead, and 1 of them was died of metastasis of lung and liver. 2 cases got lymph node metastasis, then were given surgical treatment and still alive now. 13 cases (8.0%) were DFSP-FS with their malignancies increased. 11 of them were the recurrent ones after local excision or wide excision. CONCLUSIONS: In order to avoid misdiagnosis, it is necessary for the clinician to know much about DFSP. Once the tumor was diagnosed of DFSP after local excision, it is necessary to take wide excision. Because DFSP is a malignancy of a high recurrent rate after local excision, standardized wide excision is the key in reducing local failure. Adjuvant radiotherapy is an effective treatment for the patients with positive resection margin or the patients don't suit for surgical treatment. The DFSP-FS need to use more energetic treatment in curing it.

Adolescent↗

PubMed2004

Protection of mice with a divalent tuberculosis DNA vaccine encoding antigens Ag85B and MPT64.

DNA vaccine may be a promising tool for controlling tuberculosis development. However, vaccines encoding single antigens of mycobacterium did not produce protective effect as BCG did. In the present study, we evaluated the immunogenicity and protective efficacy of a divalent DNA vaccine encoding two immunodominant antigens Ag85B and MPT64 of Mycobacterium tuberculosis. We found that both humoral and Th1-type (high IFN-gamma, low IL-4) cellular responses obtained from the divalent DNA vaccine group were significantly higher than that conferred by BCG. RT-PCR results showed that antigens were expressed differentially in various organs in divalent DNA vaccine group. The survival rate for mice treated with the divalent DNA vaccine after challenging with high doses of virulent M. tuberculosis H37Rv was significantly higher than that of the BCG group or any of the single DNA vaccine group. Significant differences were also found between the single and divalent DNA vaccinated mice in terms of body, spleen and lung weight. Bacterial loading decreased about 2000-fold in lungs and about 100-fold in spleens of divalent DNA vaccinated mice when compared with that of the control group. We conclude that our divalent DNA vaccine may be a better choice for controlling tuberculosis disease in animals.

Acyltransferases↗

PubMed2004

Single-molecule spectroscopy for nucleic acid analysis: a new approach for disease detection and genomic analysis.

Recently developed single-molecule spectroscopy (SMS) permits the analysis of fluorescent mixtures one molecule at a time. SMS methods provide the means to make rapid measurements on small, complex samples without the need for separations and target amplification enabling a new class of ultrasensitive nucleic acid assays. Here we give a brief overview of the current state of the art of SMS nucleic acid analysis and discuss ongoing work in our laboratory on two-color single-molecule fluorescence detection of specific nucleic acid sequences. In the future, two-color SMS nucleic acid assays will be used for a variety of applications including: gene expression analysis, disease detection and genomics.

DNA↗

PubMed2003

A simple quenching method for fluorescence background reduction and its application to the direct, quantitative detection of specific mRNA.

New genome sequence information is rapidly increasing the number of nucleic acid (NA) targets of use for characterizing and treating diseases. Detection of these targets by fluorescence-based assays is often limited by fluorescence background from unincorporated or unbound probes that are present in large excess over the target. To solve this problem, energy transfer-based probes have been developed and used to reduce the fluorescence from unbound probes. Although these probes have revolutionized NA target detection, their use requires scrupulous attention to design constraints, extensive probe quality control, and individually optimized experimental conditions. Here, we describe a simpler background reduction approach using singly labeled quencher oligomers to suppress excess unbound probe fluorescence following probe-target hybridization. A second limitation of most fluorescence-based NA target detection and quantification assays is the requirement for enzymatic amplification of target or signal for sensitivity. Amplification steps make quantification of original target copy number problematic because of variations in amplification efficiencies between the sequence targets and the experimental conditions. To avoid amplification, we coupled our quenching approach to a two-color NA assay with correlated, two-color, single-molecule fluorescence detection. We demonstrate a >100-fold background reduction and detection of targets present at concentrations as low as 100 fM using the two-color assay. The application of this technique to the detection and quantification of specific mRNA sequences enabled us to estimate beta-actin copy numbers in cell-derived total RNA without an amplification step.

Actins↗

PubMed2003

Cu@Au alloy nanoparticle as oligonucleotides labels for electrochemical stripping detection of DNA hybridization.

Synthesis of the novel Cu@Au alloy nanoparticle and its application in an electrochemical DNA hybridization detection assay is described in this article. We report a low-temperature method for generating core-shell particles consisting of a core of Cu and a thin layer of Au shell that can be readily functionalized with oligonucleotides. Core-shell Cu@Au particles were successfully labeled to a 5'-alkanethiol capped oligonucleotides probe that is related to the colitoxin gene. The DNA genetic sensing assay relies on the electrostatic adsorption of target oligonucleotides onto conducting polypyrrole (PPy) surface at the glassy carbon electrode (GCE), and its hybridization to the alloy particle-oligonucleotides DNA probe. Hybridization events between probe and target were monitored by the release of the copper metal atoms anchored on the hybrids by oxidative metal dissolution and the indirectly determination of the solubilized Cu2+ ions by sensitive anodic stripping voltammetry (ASV). The detection limit is 5.0 pmol l(-1) of target oligonucleotides. The Cu@Au core-shell nanoparticles combining the surface modification properties of Au with the good electrochemical activity of Cu core shows their perspective application in the electrochemical DNA hybridization analysis assay.

Biosensing Techniques↗

PubMed2003

Progress towards single-molecule DNA sequencing: a one color demonstration.

Single molecules of fluorescently labeled nucleotides were detected during the cleavage of individual DNA fragments by a processive exonuclease. In these experiments, multiple (10-100) strands of DNA with tetramethyl rhodamine labeled dUMP (TMR-dUMP) incorporated into the sequence were anchored in flow upstream of the detection region of an ultra sensitive flow cytometer. A dilute solution of Exonuclease I passed over the microspheres. When an exonuclease attached to a strand, processive digestion of that strand began. The liberated, labeled bases flowed through the detection region and were detected at high efficiency at the single-molecule level by laser-induced fluorescence. The digestion of a single strand of DNA by a single exonuclease was discernable in these experiments. This result demonstrates the feasibility of single-molecule DNA sequencing. In addition, these experiments point to a new and practical means of arriving at a consensus sequence by individually reading out identical sequences on multiple fragments.

Color↗

PubMed2003

Carbon nanotube-enhanced electrochemical DNA biosensor for DNA hybridization detection.

A novel and sensitive electrochemical DNA biosensor based on multi-walled carbon nanotubes functionalized with a carboxylic acid group (MWNTs-COOH) for covalent DNA immobilization and enhanced hybridization detection is described. The MWNTs-COOH-modified glassy carbon electrode (GCE) was fabricated and oligonucleotides with the 5'-amino group were covalently bonded to the carboxyl group of carbon nanotubes. The hybridization reaction on the electrode was monitored by differential pulse voltammetry (DPV) analysis using an electroactive intercalator daunomycin as an indicator. Compared with previous DNA sensors with oligonucleotides directly incorporated on carbon electrodes, this carbon nanotube-based assay with its large surface area and good charge-transport characteristics dramatically increased DNA attachment quantity and complementary DNA detection sensitivity. This is the first application of carbon nanotubes to the fabrication of an electrochemical DNA biosensor with a favorable performance for the rapid detection of specific hybridization.

Base Sequence↗

PubMed2003

Determination of the flavone tricin in human plasma by high-performance liquid chromatography.

Tricin is a flavone constituent of brown rice and rice bran, which interferes potently with the survival of human-derived breast and colon cancer cells in vitro. A specific and simple high-performance liquid chromatographic (HPLC) method was developed for the determination of tricin in human plasma with UV-visible detection. HPLC separation on Hypersil-BDS C(18) (4.6 x 250 mm) was carried out with an isocratic mobile phase of 52% methanol in 0.1 m ammonium acetate, pH 5.10, containing 0.27 mm disodium ethylenediamine tetraacetic acid and detection at 355 nm. The retention times of tricin and quercetin (internal standard) were 14.2 and 7.8 min, respectively. The assay was linear in the range 1-100 microg/mL (r(2 ) > or = 0.995). Tricin in plasma was efficiently extracted with 0.1 m acetic acid in acetone, and the recoveries were in the range 92.6-102.8% (n = 6) with relative standard deviation below 10% for three concentrations of tricin, 5, 10 and 100 microg/mL. The lower limit of quantitation (relative standard deviation <20%) was 1 microg/mL.

Chromatography, High Pressure Liquid↗

PubMed2003

[Combined recombinant DNA vaccine results in significant protection against Mycobacterium tuberculosis].

Three proteins secreted from Mycobacterium tuberculosis, Ag85B, ESAT-6 and MPT63 were selected as antigens for making combined DNA vaccine by immunizing mice. The immune response induced by the vaccine and its protective efficacy were studied. It was demonstrated that when mice were immunized with the combined DNA vaccine, the titer of antibody for Ag85B in serum increased to more than 10(5), but the titers of ESAT-6 and MPT63 specific antibodies were undetectable. After the final immunization, the level of gamma specific for Ag85B, ESAT-6 and MPT63 reached (17.0+/-7.0) u/ml, (6.0+/-0.8) u/ml and (11.9+/-8.0) u/ml, respectively. Mice, that were inoculated with the empty eukaryotic expression vector pJW4303 DNA, produced negligible amounts of antigen-specific INF-gamma. The combined DNA vaccine resulted also in significantly reduced amount of bacteria in the lungs of experimental mice. Microphotographs showed clearly that these lungs were better protected against Mycobacterium tuberculosis challenge than control mice. The combined DNA vaccine reported in this work shed new lights on the prophylactic protection against tuberculosis.

Acyltransferases↗

PubMed2003

[The 102 kb pigmentation (pgm) locus of Yersinia pestis isolated from Microtus brandti].

OBJECTIVE: To find out the differences between 102 kb pgm locus of Yersinia pestis isolated from Microtus brandti with of other types, and the characters of Yersinia pestis isolated from Microtus brandti caused by their makeup of the 102 kb pgm locus. METHODS: 102 kb pgm locus of Yersinia pestis isolated from Microtus brandti and Yersinia pestis isolated from Marmota himalayana were amplified by polymerase chain reation (PCR) with 25 pair of nested primers. The PCR products of one pair of primer were obviously different, and then cloned and sequenced. Sequences were searched against current protein and nucleotide databases, using BLAST. RESULTS: The 102 kb pgm locus of Yersinia pestis isolated from Microtus brandti was devoid one IS100. In addition, it had more copies than other types in the similar variable-number tandem repeat sequences. CONCLUSION: The 102 kb pgm locus of Yersinia pestis was different from that of other types. It had only one IS100 flanked it, which corresponded to the character that its pgm(+) phenotype was stable. Further study was needed to confirm the relationship between the diminution virulence of Yersinia pestis isolated from Microtus brandti and the loss of IS100 and other changes.

Animals↗

PubMed2003

[Study on extraction separation of Bi(III), Fe(III), Cu(II), Ni(II), Co(II) and Pb(II) in PEG-(NH4)2SO4-PR system using spectrophotometry].

In polyethylene PEG-(NH4)2SO4-PR system the extraction separation behaviour of the complexes of Bi(III), Fe(III), Cu(II), Ni(II), Co(II) and Pb(II) was investigated. The results indicated that Bi in pH 3.5-6.5 and Fe(III) in pH 4.0-7.0 were almost completely extracted by the PEG phase, while Cu(II) and Co(II) in pH 1.0-7.0, Pb(II) in pH 2.0-7.0, and Ni(II) in pH 1.0-4.5 were not extracted by the PEG phase. So Bi(III) (pH 3.5) and Fe(III) (pH 5.0) were quantitatively separated from the mixed solution of Bi(III), Fe(III), Cu(II), Co(II), Pb(II) and Ni(II) ions. The extraction mechanism for PEG phase was preliminarily studied.

Ammonium Sulfate↗

PubMed2003

[Detection and identification of phytoplasma strain associated with periwinkle yellows].

A 1.2kb and 1.3kb DNA fragments were amplified in DNA samples extracted from periwinkle exhibiting yellows naturally. The amplified fragments were cloned, sequenced and compared with other phytoplasma strains. The results showed that the 16S rDNA and ribosomal protein gene of periwinkle yellows phytoplasma consist of 1239bp and 1244bp, respectively. They all shared high homology (higher than 97.5%) with phytoplasma strains of 16S rI group. Thus, the result made it clear that the phytoplasma strain of periwinkle yellows (PY) is one of the members of phytoplasma 16SrI group.

Catharanthus↗