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B Dai

Publications and source records attributed to B Dai.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Cloning, characterization and expression in E. coli of the flagellin gene from Leptospira interrogans Serovar lai].

To obtain a large amount of recombinant endoflagellin protein of leptospsira, we have cloned the fla B gene from Leptospira interrogans serovar lai strain 017, which encodes the core flagellar protein. The entire open reading frame was amplified by polymerase chain reaction, which was digested with endonucleases Sal I and Cla I, then was orientationally cloned into the expression vector, pT7-7. The recombinant plasmid was transformed into Escherichia coli JM109 (DE3) for expression. After induction with IPTG, a 34 kd expression protein was detected by SDS-PAGE. The amount of recombinant protein was estimated as 11.8% of the whole bacterial lysate proteins. Probed with insert fragments, Southern blot analysis indicated that possibly two gene related to fla B were present in the genome of Leptospira interrogans serovar lai stain 017. Western blot analysis showed that the 34 kd expression protein reacting with rabbit polyclonal antiserum raised against leptospira endflagellin.

Cloning, Molecular↗
PubMed1998

[Analysis of molecular karyotype of Leishmania isolates from hilly foci and plain foci of China].

AIM: To analyse the molecular karyotypes of Leishmania isolates from hilly and plain foci of China. METHODS: Pulsed field gel electrophoresis(PFGE) was performed in 1% agarose at 6 V/cm in 0.5 x TBE at 14 degrees C with a pulse time of 60 s for 15 h and a pulse time 90 s for 9 h. RESULTS: Each isolate was resolved into 15 different EtBr-staining bands ranging in size from 200 to 2,200 kb, in which the karyotypes of 6 isolates from hilly foci were similar (including karyotypes of canine isolates similar with those of human isolates), and they were partly similar with those of L. infantum. The karyotypes of the two isolates from plain foci were similar, but the isolates from the two topographically different foci were different from each other. CONCLUSION: Homology exists between L. d. isolates from hilly foci and plain foci respectively, and exists in part between L. d. isolates from hilly foci and L. infantum; while heterogeneity exists between L. d. isolates from hilly foci and plain foci. The reservoir host, domestic dog, plays an important role as the infection source of leishmaniasis in the hilly foci of China.

Animals↗
PubMed1997

First trial of home ECG and blood pressure telemonitoring system in Macau.

OBJECTIVE: To determine the feasibility of home monitoring of patients with cardiac disease or hypertension. METHODS: An improved home electrocardiographic and blood pressure telemonitoring system linked to a central workstation was tested in 10 patients in Macau for 3 months. RESULTS: The total number of connections was 1377. Of the automatic alarm connections, 32.5% were false positive, with the percentage of false positives ranging from 7.6 to 54.6 for different patients. Both patients and physicians found the system easy to use. CONCLUSIONS: Further investigation is required to match the number of patients with the system capacity. A more robust dysrhythmia detection algorithm is needed to reduce the number of false alarms. Nevertheless, the results were sufficiently good that the trial is being expanded.

Blood Pressure Determination↗
PubMed1997

Cloning of the functional promoter for human insulin-like growth factor binding protein-4 gene: endogenous regulation.

The majority of the colon cancers analyzed to-date express insulin-like growth factor binding protein (IGFBP)-4, and antisense inhibition of IGFBP-4 messenger RNA (mRNA) confers a growth advantage to the cells in response to endogenous and exogenous IGFs. We recently reported a significant up-regulation of IGFBP-4 expression in a human colon cancer cell line (CaCo2) on spontaneous differentiation of the cells in culture. This suggests that the expression of IGFBP-4 may be related to growth and differentiation of colon cancer cells. To study the endogenous factors involved in the transcriptional regulation of IGFBP-4, we have isolated and sequenced the human (h) IGFBP-4 promoter. The approximately 1.3 kilobase pair (kb) 5' flanking region of the IGFBP-4 gene is GC rich and possesses several potential regulatory elements. These elements include a typical TATA box with sequence TATAA, located -299 nt from the initiation ATG codon. The cap site is located 14 nt downstream of the TATA box as determined by primer extension analysis. A 1.4-kb DNA fragment including the 1.254 kb 5' flanking region of the hIGFBP-4 gene was subcloned into a luciferase reporter vector (pGL-2 basic) either in the sense (BP-4-S-pGL) (S) or antisense (BP-4-AS-pGL) (AS) (negative control) orientation, relative to the luciferase coding sequence in the vector. CaCo2 cells were transfected with either the S or the AS vectors on days 2-10 of culture; cotransfection with the SV40-beta-Galactidose (Gal) vector was used to correct for transfection efficiency. The ratio of luciferase/beta-Gal expression by CaCo2 cells transfected with the S vectors increased significantly from days 3 and 4 to days 5 and 6 of culture, followed by a sharp decline on days 7-9, resembling the pattern of endogenous expression of IGFBP-4 by the cells; the expression of luciferase by the AS vectors remained low and insignificant. These results thus suggest that the approximately 1.4 kb 5' flanking region of the IGFBP-4 gene contains the cis elements required for regulation of the IGFBP-4 gene. Cloning and sequencing of the functional hIGFBP-4 promoter will enable us, for the first time, to study the endogenous factors/mechanisms responsible for the growth/differentiation (cell density) associated regulation of IGFBP-4 expression in colonic epithelial cells.

Base Sequence↗
PubMed1997

A home electrocardiography and blood pressure telemonitoring system.

A home electrocardiography (ECG) and blood pressure telemonitoring system for cardiac patients was installed in the Macau region. The monitoring centre was established in the emergency unit at the Government Hospital of Macau. The first users were 10 cardiovascular patients selected by a physician. The average age of these users was 61 years (range 30-78). The results of a three-month trial showed that the system was easy to operate and technically reliable. It was found to be helpful for cardiac patients. The most significant problem during the trial was electrical noise from the ECG electrodes.

Adult↗
PubMed1997

[Immunogenecity of expressed protein p68 from recombinant plasmid rpDJt in L. interrogans serovar lai].

There are two types of infection caused by pathogenic microorganisms, intracellular infection and intercellular infection. Infection of pathogenic leptospira is an intercellular infection. The immunological reaction of host to intercellular infection is unique. The potential immunogen of an expressed protein should meet three criteria: it can be degraded (by antigen-present cells in the host); it should have antigenic epitope which can be recognized by specific antibodies and have at least one epitope that can be recognized by an MHC II protein and T cell receptor. In this study we report the cloning of an L. interrogans protein in plasmid rpDJt and the immunogencity of the expressed protein derivative. A genomic library of L. interrogans serovar lai strain 017 was constructed with the plasmid vector pUC18. Recombinant plasmids, designated pDJH2 and pDJ8 were screened from the bank. EcoRI-inserted fragment of 1. 9 kb recombinant DNA of pDJH2 was ligated into T7 RNA polymerase/promoter vectors (pT7-7). Then they were transformed into E. coli JM109 (De3), one of subclones, designated rpDJt was achieved. SDS-PAGE showed that the molecular weights of expression proteins were 68 kd and 23 kd respectively, designated p68 and p23. Purifying and isolating p68 and p23, we separated them from SDS-Polyacrylamide gels by using Side-Strip method. After fragmenting and electroeluting, p68 and p23 were injected into guinea pigs and rabbits. An extremely strong immune response to p68 was obtained since an anti-p68 antibody response could be detected to a dilution 1:524,288 (guinea pigs) and 1:262,144 (rabbits) by ELISA while anti-P23 antibody being 1:1024 (the same to guinea pigs and rabbits). The results of improved MTT and conA 3HTdR transformation methods showed the activities and proliferation of Th-cells were increased in guinea pigs after p68 immunization (IL-6, 83.25 IU/ml, IL-2, 28.75 IU/ml; RPI, 2.04, SI, 65.62%) Thlymphocyte existed in two subclasses, the Th1- and Th2-cells. A major role of Th2-cells is to "help" B-cells differentiate, replicate, and secrete antibody. The properties of these interactions explain why p68 makes good antigen and p23 does not. The antigens responsible for eliciting the production of protective antibodies are not known; however, several outer membrane proteins on L. interrogans are candidates for vaccine. Our results suggest that expresion protein p68 from recombinants (rpDJt) may be a candidate for gene engineered subunit vaccine for Leptospirosis.

Animals↗
PubMed1997

[Characterization of immunoblots of hydrophobic outer membrane proteins Leptospira interrogans serovar lai strain 017].

Outer membrane proteins (OMP) of Leptospira interrogans serovar lai strain 017 were extracted by using Triton X-114 (TX-114). The OMP were solubilized and phase partitioned into both the hydrophilic, aqueous phase and hydrophobic, detergent phase. TX-114 did not solubilize the protoplasmic cylinder in intact organisms. The protoplasmic cylinders contained a lot of protein bands and most of the TX-114 solubilized proteins partitioned into the aqueous phase, whereas only 14 protein bands entered the detergent phase with SDS-PAGE. Detergent phase proteins were of 5 major protein bands such as 66 kd, 39 kd, 35 kd, 27 kd, and 16 kd. Immunoblotting of the material extracted with TX-114 showed that detergent phase proteins of alone 39 kd was apparently immunoblotting with antiserum against such as whole cell of 017 strain the outer envelope of 017 strain and the immunoprotective anti-017 Mb E4B7G5. The results showed that we could separate and purify the 39 kd protein to analyse the amino acid sequence for the cloning, expression and development of genetic engineering vaccines.

Bacterial Outer Membrane Proteins↗
PubMed1997

[Construction of genomic library of L. interrogans serovar lai using lambda gt11 as the vector and a study of recombiant plasmid pDL121].

A genomic library of L. interrogans serovar lai strain 017 has been constructed using lambda gt11 as the vector. DNA was partially digested by two blunt-end restriction enzymes, then methylated with EcoR I methylase; after EcoR I linker was added to the DNA, the linker-ended DNA was ligated to the dephosphorylated EcoR I digested lambda gt11 arms. The recombined DNA was packaged in vitro, and used to transduct E. coli Y1090 for amplification. There were 2.1 x 10(6) recombinant bacteriophages as recognized by their ability to form white plaques plated on Lac host in the presence of both IPTG and X-Ga1. A positive clone, designated lambda DL12, was screened with a rabbit anti-serum against L. interrogans serovar lai from the genomic library. The DNA from lambda DL12 was subcloned into plasmid pUC18. A recombinant (designated as pDL121) was obtained. SDS-PAGE analysis indicated that a 23 kd was expressed in E. coli JM 103 harboring pDL121. Western blotting analysis showed that a specific protein band molecular weight of 23 kd could be recognized by the rabbit antiserum against L. interrogans serovar lai strain 017.

Cloning, Molecular↗
PubMed1997

PCR amplification, molecular cloning, DNA sequence analysis and immuno/protection in BALB/C mice of the 33 kDa endoflagellar protein of L. interrorgans serovar lai.

A pair of oligonucleotide primers were designed to amplify the endoflagella gene of L. interrogans serovar lai. An approximately 840 bp fragment was generated with PCR and inserted into plasmid pUC8, after the fragment and pUC8 were digested respectively with BamHI and PstI. A recombinant plasmid (designated as pLF1) was obtained. SDS-PAGE analysis indicated that a 33 kDa was expressed in E. coli JM103 harboring pLF1 and the expression level of the protein was 11% of the total bacterial soluble proteins. Western blot analysis showed that the protein band could be recognized by the antiserum against the endoflegella (Axial filament) of Leptospira interrogans serover lai. Nucleotide sequence data showed an open reading frame encoding 282 aminoacids residues, corresponding to a protein of molecular weight 33.6 kDa. Comparison of the deduced endoflagellar subunit protein (flaB) amino acid sequence with flagellins from other bacteria revealed a high level of identity with the Treponema pallidum flaB proteins. Immunization/protection experiment was performed on the model of BALB/C mice and showed that there was higher survival rate in the group JM103-pLE1 than in the group JM103-pUC8.

Amino Acid Sequence↗
PubMed1996

Gastrin gene expression is required for the proliferation and tumorigenicity of human colon cancer cells.

The majority of human colon cancers express the gastrin gene, and a significant percentage bind gastrin-like peptides. However, it is not known if gastrin gene products are physiologically relevant to the growth and proliferation of human colon cancers. To investigate the functional role of gastrin gene expression, we examined the effect of gastrin antisense (AS) RNA expression on the growth and tumorigenicity of colon cancer cells. The full-length human gastrin cDNA was cloned in the AS direction in a retroviral vector under the transcriptional control of human cytomegalovirus promoter. Three representative human colon cancer cell lines that expressed negligible (Colo-205A) to significant (Colo-320 and HCT-116) levels of gastrin mRNA were transfected with either AS or control vectors and subjected to various growth studies in vitro and in vivo. The proliferative and tumorigenic potential of the AS clones from the gastrin-expressing cell lines was significantly suppressed compared to that of the control clones, whereas the growth of Colo-205A-AS cells (the negative control) was similar to that of the Colo-205A-C-cells, indicating the relative specificity of the antitumorigenic effects of AS gastrin RNA expression. We believe that this is the first evidence that supports a possible critical role of gastrin gene expression in the tumorigenicity of human colon cancers that express the gastrin gene. Because > 60-80% of human colon cancers express the gastrin gene, it can be expected that the growth of a significant percentage of these cancers may be critically dependent on the expression of gastrin gene products. Therapeutic measures, such as the AS strategy used in the present study, may therefore prove to be useful in treating human colon cancers in the future.

Animals↗
PubMed1996

The design and preliminary evaluation of a home electrocardiography and blood pressure monitoring network.

A home electrocardiography (ECG) and blood pressure (BP) monitoring network was established in Beijing. The network consisted of three parts: (1) the home ECG and BP monitoring devices; (2) the monitoring centre at the hospital; and (3) the data communication network, for which we chose the public telephone network. The system was tested in our university hospital for two months with 30 patients and six normal volunteers. A preliminary evaluation by the users indicated that the system was acceptable in terms of its efficiency and effectiveness. This paper describes the system design, the preliminary testing procedure, and results.

Adult↗
PubMed1996

Proliferation and differentiation of a human colon cancer cell line (CaCo2) is associated with significant changes in the expression and secretion of insulin-like growth factor (IGF) IGF-II and IGF binding protein-4: role of IGF-II.

The extent to which the insulin-like growth factor (IGF) system contributes to the initiation and progression of colon cancer remains poorly defined. We recently reported that a majority of human colon cancers express and secrete the potent mitogen IGF-II and at least two inhibitory binding proteins, IGFBP-2 and IGFBP-4. In the present study we measured the expression and secretion of IGF-II, IGFBP-2, and IGFBP-4 in relation to growth and differentiation of CaCo2 human colon cancer cells, which undergo spontaneous enterocytic differentiation in culture. Under the conditions of the present study, CaCo2 cells demonstrated an initial rapid phase of growth between Day 2 through days 7-9 of culture, followed by a significant retardation in the growth between days 9-13. Alkaline phosphatase (ALP) activity, a marker of enterocytic differentiation, progressively increased between Days 7-13 in culture, temporally correlating with post-confluent phase of negligible growth. These changes in growth and differentiation were accompanied by > 80% decline in the relative concentration of IGF-II messenger RNA (mRNA) between Days 2-13. In contrast, the relative mRNA concentrations of inhibitory binding proteins (IGFBP-2 and IGFBP-4) increased rapidly to 200% of Day 2 values by Days 5-7 before returning to baseline levels by Day 13. The relative protein concentrations of the three factors measured in the conditioned media of the cells followed a pattern very similar to that measured for the mRNA levels. While the changes in the relative protein concentrations and mRNA levels of IGF-II and IGFBP-4 were statistically significant, the changes measured in the RNA and protein levels of IGFBP-2 were not, as a result of large inter experimental variations. Thus these results suggested that CaCo2 cell differentiation may require an attenuation of IGF-II effects. To confirm the latter possibility, additional studies were conducted with a specific neutralizing antibody against IGF-II. Incubation of CaCo2 cells with anti-IGF-II antibodies from Day 0 through Day 7 significantly retarded the growth of the cells and was accompanied by a significant increase in the concentration of Alkaline phosphatase activity per 10(6) cells. Recently, we reported a potent inhibitory role of IGFBP-4 in the growth of colon cancer cells. In the present studies, a possible important role of IGF-II is illustrated not only in the growth but also in the differentiation of colonic cells. Our studies thus suggest that differential expression of IGF-II and IGFBPs may be playing a critical role in both proliferation and differentiation of colonocytes.

Alkaline Phosphatase↗
PubMed1996

Medical services in urban China: does the 'free' care policy induce greater demand?

In this paper we discuss the nature of the medical services and the free medical care programs in urban China, then using the data collected in a large city, we also explored the differences between those covered by a free program and those not in perceived illness, doctor visit, hospital admission, and emergency use. Our findings may show that Chinese experience in medical service use is consistent with the common idea that a free medical care policy could induce greater demand while it also has its own nature.

China↗
PubMed1996

[Malaria in Vietnam in 1996: brief synthesis of epidemiological data].

Vietnam is in a tropical region where malaria is considered as a public health problem. Plasmodium falciparum is responsible for 72% of cases of malaria and Plasmodium vivax for 28%. Analysis of available data shows that the situation is complex. The overall incidence of malaria is low, i.e. approximately 8.5: 1000 in 1995 but the disease is unevenly distributed over the country which has a variety of terrain and climates. Hilly and mountainous areas are the most affected especially in the center of the country where the annual incidence can exceed 10%. In most provinces, the majority of people are not immunized and malaria is unstable. Emergence of chemoresistant parasites is a major problem. Resistance rates of Plasmodium falciparum ranges from 40.78% to 61.67% for chloroquine and from 25.80% to 47.40% for sulfamides. Locally produced artemisinin derivatives are being more and more widely used in order to cope with this problem local. Given the great epidemiological variability of malaria in Vietnam, careful analysis needed before attempting any type of group and individual prophylaxis.

Cause of Death↗
PubMed1996

[The PCR amplification, cloning, sequencing, expression in E. coli of gene encoding endoflagella subunit protein (fla B) from Leptospira interrogans serovar lai].

A pair of oligonucleotide primers were designed by ourselves to amplify the endoflagella gene of L. interrogans serovar lai. A fragment about 840 bp was generated with PCR and inserted into plasmid pUC8 after the fragment and pUC8 were digested respectively with Bam HI and Pst I. A recombinant plasmid (designated as pLF1) was obtained. SDS-PAGE analysis indicated that a 33 kd was expressed in E. coli JM103 harboring pLF1 and the expression level of the protein was 11% of total bacterial soluble proteins. Western blot analysis showed that the protein band could be recognized by the antiserum against the endoflagella (Axiall filament) of Leptospira interrogans serovar lai. Nucleotide seguence data showed an open reading frame encoding 282 aminoacids residues, corresponding to a protein of molecular weight 33.6 kd. The G + C content of endoflagella subunit protein gene was 48 mol%. Therefore, the G + C content of the leptospiral fla B Gene is significantly higher than the reported 39 mol% G + C content of leptospiral genome of L.interrogans serovar lai but similar to the G + C of the Treponema pallidum genome. Comparison of the deduced endoflagellar subunit protein (fla B) amino acid sequence with flagellins from other bacteria revealed a high level of identity with the Treponema pallidum fla B proteins. Immunization/protection experiment was performed on the model of BALB/c mice and showed that the survival rate in the group JM103-pLF1 was higher than that in the group JM103-pUC8, but statistically the difference between them was significant (P < 0.05) and pLF1 did not induce significant levels of agglutinating antibodies against L.interrogans serovar lai.

Amino Acid Sequence↗
PubMed1996

[Research on the recombinant plasmid pDJH2 of L. interrogans serovar lai: sequencing and alignment with other known bacterial Omp sequence].

The Leptospira whole cell vaccine (LWCV) currently used in China is safe and effective, out the immunity following vaccination with two doses of the fluid medium vaccine is of low order. The duration of immunity conferred by this vaccine is rather short, six months or at most one year. Therefore, it is necessary to develop new generation vaccines against Leptospirosis for the developing world. In this paper we report the sequencing of the insert fragment of pDJH2 from genomic DNA of L. interrogans sevovar lai strain 017 and its alignment with other bacterial omp sequences. A genomic library of Leptospira interrogaans serovar lai strain 017 was constructed with the plasmid vector pUC18. A recombinant plasmid designated pJDH2 was screened from the genomic library. Inserted fragment of pDH2 is 1.9 kb by gel electrophoresis. Immunization/protection was studied in BALB/c mice model. The results showed highly significant difference between pDJH2 and pUC18 (control). Inserted fragment of pDJH2 DNA sequencing was performed by Dr Yan Zhengxin (Max-Planck-Institut for Biology. Tubingen, Germany). Insert fragment was cloned into pBluescript II KS-(stratagene) and sequenced by using AB1 (Applied Bio Systems, Model 373A). Two open reading frames of 565 and 662 nucleotides were identified. There were identifiable initiation codons, terminators, Shine-Dalgano ribosome combining site, Pribnow boxes and Sextama boxes within the 2 sequenced regions. Nucleotide sequences were analysed using Gene Work, a suit of computer program developed by Department of Biochemistry St. Jude Children's Research Hospital Memphis. U.S.A. The results of formatted alignment showed the predicted nucleotide sequence of ORF1 of the serovar lai had significant similarity with ORF2 (49.36%). L. kirschneri ompL1 (49.26%), Borrelia burgdoferi omp (48.97%), Treponema phagedenis omp (47.3%); Salmonella typhimurium ompC(46.87%), Yersinia enterocolitica ompH (46.7%), Leptospira borgpeterseni pfap (46.3%), and Serratia marcescens omp (43.3%). The close relationship of the pDJH2 ORF1 and ORF2 nucleotide sequences from Leptospira kirschneri ompL 1 is apparent. Whether the recombinant pDJH2 will prove useful for vaccine development remains to be tested.

Animals↗
PubMed1996

[Subclones of fragment DNA recombinant rpDJH2 of L. interrogans serovar lai strain 017 and it's expression of high level in E. coli].

Fragment of 1.9 kb recombinant DNA of pDJH2 was linked with vectors pT7-7 and pRSETs. Then they were transformed into E. coli JM109 (DE3) respectively. Expression of subclones was achieved in E. coli JM109 (DE3) with IPTG inducement. SDS-PAGE showed that the molecular weights of products were 68kd and 23 kd respectively. The amount of production seemed to be higher than that of the outer membrane proteins of L. interrogans serovar strain 017 in nature. Immunoblotting of pDJt and pDJrB2 (both are subclones) with the specific antiserum of anti-OMP of L. interrogans serovar lai strain 017 and the experiment of initiative immuno-protection in guinea pigs showed both protein-68 kd and 23 kd might be the antigens of immuno-protection on the outer membrane of L. interrogans serovar lai strain 017.

Animals↗