Biomedical subjects

B Dai

Publications and source records attributed to B Dai.

At least 19 recordsLinked to original sources

PubMed2006

The 44 kDa Pim-1 kinase directly interacts with tyrosine kinase Etk/BMX and protects human prostate cancer cells from apoptosis induced by chemotherapeutic drugs.

Protein kinase Pim-1 has been implicated in the development of hematopoietic and prostatic malignancies. Here, we present the evidence that two isoforms, the 44 and 33 kDa Pim-1, are expressed in all human prostate cancer cell lines examined. The subcellular localization of human 44 kDa Pim-1 is primarily on the plasma membrane, while the 33 kDa isoform is present in both the cytosol and nucleus in PCA cells. The 44 kDa Pim-1 contains the proline-rich motif at the N-terminus and directly binds to the SH3 domain of tyrosine kinase Etk. Such interaction leads to the activation of Etk kinase activity possibly by competing with the tumor suppressor p53. This is corroborated by the fact that overexpression of the 44 kDa Pim-1 in prostate cancer cells confers the resistance to chemotherapeutic drugs. Our results suggest that these two isoforms of Pim-1 kinase may regulate distinct substrates and the 44 kDa Pim-1 may play a more prominent role in drug resistance in prostate cancer cells.

Amino Acid Sequence↗

PubMed2001

[Tumor targeted expression of adenovirus mediated CDglyTK gene regulated by irradiation via Egr-1 promoter].

OBJECTIVE: To construct adenoviral vecter of AdEgr-CD/TK in which CDglyTK gene was driven by Egr-1 promoter, and control the tumor targeted expression of CDglyTK gene by gamma irradiation so as to observe the effects of gene-radiotherapy of liver cancer. METHODS: Adenoviral vector of AdEgr-CD/TK was generated through homologous recombination in bacteria. The expression of CDglyTK gene in MM45T. Li cells infected with AdEgr-CD/TK and exposed to different doses of gamma irradiation were analyzed, and the relative survival rate of the cells in presence of prodrugs 5-FC and GCV was tested. In addition, the tumor suppression effects of different treatments were investigated in 64 mice bearing liver cancer by observing the size of tumor at interval of four days. RESULTS: In vitro experiment showed that gamma irradiation markedly and dose-dependently induced CDglyTK expression in MM45T. Li tumor cells, and significantly enhanced the sensitivity of MM45T. Li cells infected with AdEgr-CD/TK to prodrugs 5-FC or GCV resulting in cell being killed (P < 0.01). A synergetic cytotoxic effect was found when both 5-FC and GCV were added. In vivo experiment revealed that, compared with other control treatments, intratumoral injection of AdEgr-CD/TK combined with intraperitoneal injection of GCV + 5-FC and TLI obviously suppressed tumor growth (P < 0.01), with 30% of the tumor eradicated completely while without causing the increase of whole body cytotoxic effect. CONCLUSION: Tumor targeted expression of CDglyTK gene under the control of irradiation represents a novel strategy for safe and effective gene therapy of cancer and might have wide application in the future.

Adenoviridae↗

PubMed2001

Recording of spared motor evoked potentials and its augmentation by 4-aminopyridine in chronic spinal cord-injured rats.

OBJECTIVE: To research the direct electrophysiological evidence of discomplete spinal cord injury (SCI) and the effect of 4-aminopyridine on it. METHODS: Motor evoked potentials (MEPs), both spinal cord recorded MEPs (scMEPs) and extracellularly recorded MEPs (exMEPs) were recorded and characterized on a T13 epidural electrode (scMEPs) and an extracellular microelectrode (exMEPs) for 10 normal rats and 40 rats with lesions of various severity (sham, 35 g.cm force (gcf), 70 gcf, 100 gcf impact injury) at the T8-T9 cord using the Allen's drop model. The incline plane and Tarlov techniques were used to assess clinical neurological function. RESULTS: MEPs in the normal rats were elicited by applying transcortical suprathreshold stimulation consisting of 3-4 early negative peaks (N1, N2, N3 and N4) followed by several late waves. The N1 and N2 peaks were largest in the anterior and ventrolateral funiculus, respectively, which was indicative of extrapyramidal pathways. The 100 gcf impact injuries and the cord transection abolished the MEP distal to the lesion, whereas the 35 gcf injuries resulted in a latency shift and amplitude decrement of the MEP peaks. Eighteen of the 20 rats with 70 gcf-injuries showed clinical paraplegia. Among them, 7 rats had neurophysiological evidence of residual conduction pathways through the lesioned cord segment, such as the presence of N1 and N2 peaks in the scMEPs or exMEPs. After 4-aminopyridine (4-AP) administrations (1 mg/kg), the amplitude of the spared exMEP increased significantly and spread more widely. CONCLUSIONS: MEPs evoked by transcortical stimulation travel mostly in the extrapyramidal tract. MEP monitoring could provide an excellent method of detecting the functional integrity of the motor tracts after SCI, and could even detect spared motor fibers after discomplete SCI. Furthermore, the use of 4-AP or other K+ channel blocking agents may be a potential treatment for patients with chronic moderate to severe SCI.

4-Aminopyridine↗

PubMed2001

[Changes in cyclin expression during proliferation and differentiation of CD34(+) cells derived from fetal liver induced by thrombopoietin].

In order to elucidate the intrinsic mechanism underlying proliferation and differentiation of megakaryocytes during ontogenesis, CD34(+) cells were isolated from human fetal liver (FL) with a high-gradient magnetic sorting system (MACS) and were incubated in liquid suspension with 50 and 100 ng/ml of thrombopoietin (TPO) and in MegaCult(Tm) -C semi-solid culture system with 0, 12.5, 25, 50, 100, and 200 ng/ml of TPO. The cell number, colony number of CFU-Mk, platelet-associated antigen phenotype, and DNA ploidy of CD41(+) cells were examined from d 0 to d 12 in culture. The expression patterns of cyclins B1, D1, and D3 were also analyzed by using immunoblot and flow cytometry. TPO stimulated proliferation of CD34(+) cells of FL from 1 x 10(5)/ml to 13.12 +/-4.06 10(5)/ml with 95% of CD41a(+) cells and 3% of CD34(+) cells after 12 d of culture. Most of the megakaryocytes (MKs) derived from FL were in 2 N ploidy class, and few in 4 N ploidy class, but no megakaryocytes ploidy class was higher than 4 N. The effect of TPO on the formation of CFU-Mk colonies from FL derived CD34(+) cells is shown in a dose-response curve. The expression of cyclin B1 increased progressively and the high level of cyclin B1 was maintained in FL CD34(+) cells induced by TPO during 12 d of culture. A high level of cyclin B1 appeared on FL derived MKs of G1 phase at d 12. The expression of cy-of cyclins D1 and D3 gradually increased in FL CD34(+) cells, which was induced by TPO during the initial 6-day incubation. Afterwards, the level of cyclins D1 and D3 decreased progressively, particularly in MKs which were in G2+M phases. These data suggest that (1) TPO induced proliferation and differentiation of FL derived CD34(+) cells through upregulation of cyclin B1 in G2+M phases and cyclins D1 and D3 in all phases of cell cycle, and (2) Continuing high level of cyclin B1 and decreases of cyclins D1 and cyclin D3 on MKs in G2+M phases may contribute to a retardation of MK endoreduplication.

Antigens, CD34↗

PubMed2001

[One stage otoplasty treatment for congenital malformations of the auricle and middle ear].

OBJECTIVE: To investigate the application of one stage otoplasty for congenital atresia of the external acoustic canal and malformations of the middle ear and the auricle. METHOD: Patients with the ear malformations were given surgical reconstruction of one stage otoplasty. The auricle was reconstructed with the rib which was encapsulated with the superthin temporal flap. According to the malformations of the middle ear in patients, I style tympanoplasty and III style tympanoplasty were carried out respectively. All patients were performed myringoplasty with temporal fascia and reconstructed the external acoustic canal with full thickness skin-grafting. RESULT: A long term follow-up (4-6 years) demonstrated that 11 ears were survival of which 8 ears figuration were ideal. The hearing improvement was observed in all patients. CONCLUSION: One stage otoplasty is effective for treatment of the congenital malformations of the external and middle ear.

Adult↗

PubMed2000

Identification of a novel cis element required for cell density-dependent down-regulation of insulin-like growth factor-2 P3 promoter activity in Caco2 cells.

The activity of the exogenous, full-length insulin-like growth factor-2 (IGF-2) P3 promoter is significantly up-regulated during the logarithmic growth phase but rapidly declines in confluent CaCo2 cells undergoing differentiation. Nuclear run-on assays confirmed cell density-dependent regulation of endogenous P3 promoter. To identify regulatory elements in the P3 promoter that may be required for regulating cell density-dependent transcriptional activity, we used the methods of promoter truncation, electrophoretic mobility shift assay, DNase footprinting, and mutation analysis. The relative activity of the full-length (-1229/+140) and truncated (-1090/+140) promoter was identical, being approximately 19, 27, 7, and 3% of pSV-luc activity on days 3, 5, 7, and 9 of cell culture, respectively. However, truncation to -1048 resulted in complete loss of cell density-dependent down-regulation of P3 promoter activity on days 7 and 9, suggesting the presence of regulatory elements between -1091 and -1048 sequence. Further stepwise truncation to -515 did not change promoter activity. Truncation to -138/+140 resulted in complete loss of promoter activity, suggesting that the core promoter was within the -515/-138 segment. A 14-base pair footprint (-1084/-1070) was identified by DNase footprinting within the distal -1091/-1048 segment. Electrophoretic mobility shift assay with wild type and mutant probes confirmed the presence of a novel 7-base pair (CGAGGGC) (-1084/-1078) cis element (P3-D); its mutation abolished binding. Functionality of P3-D cis element was confirmed by measuring the activity of core P3 promoter ligated to distal P3 segment containing either the mutant or wild type P3-D element. We have, therefore, identified a novel cis element, P3-D, that appears to play a critical role in regulating IGF-2 P3 promoter activity in a cell density/differentiation-dependent manner.

Base Sequence↗

PubMed2000

Autocrine gastrins in colon cancer cells Up-regulate cytochrome c oxidase Vb and down-regulate efflux of cytochrome c and activation of caspase-3.

Suppression of the gastrin gene in human colon cancer cells by stably expressing antisense (AS) gastrin RNA results in significant growth suppression of AS cells. To understand mechanisms mediating the growth effects of autocrine gastrins, differential expression of transcripts by AS and control (C) clones of a representative cell line (HCT-116) was analyzed to identify target genes of autocrine gastrins. Six differentially expressed transcripts were confirmed and sequenced. Of these, the RNA and protein levels of cytochrome c oxidase (COX) Vb were significantly higher in C versus AS cells. The expression of COX Vb by colon cancer cells was proportional to the expression of gastrin. Higher levels of COX Vb coprecipitated with cytochrome c in the mitochondria of C versus AS cells. Treatment of mitochondria with digitonin resulted in a 2-fold higher release of cytochrome c from AS versus C mitochondria. As a corollary, the cytosolic levels of cytochrome c were significantly higher in AS versus C cells, which correlated with approximately 2- and approximately 3-fold higher activation of caspase-9 and -3, respectively, in AS versus C cells in response to camptothecin. Thus, autocrine gastrins may support growth/survival of cells by up-regulating COX Vb, which may decrease the sensitivity of the cancer cells to apoptotic stimuli by increasing retention of cytochrome c in mitochondria.

Colonic Neoplasms↗

PubMed2000

Role of autocrine and endocrine gastrin-like peptides in colonic carcinogenesis.

Colon carcinogenesis is a multistep process that involves deletions, mutations, and changes in expression of genes that regulate growth, differentiation, and apoptosis. Hyperproliferation can initiate dysplastic growth, resulting in accumulation of genetic defects and progression of colon cancer. Although genetic instability, because of inheritance of specific genetic defects, plays a dominant role in familial cancers, in the majority of sporadic cancers hyperproliferation is likely to play a permissive role in initiation and progression of the disease. Thus factors that regulate growth, differentiation, and apoptosis are likely to play an important role in colon carcinogenesis. Autocrine gastrins, insulin-like growth factor-II, transforming growth factor-alpha, and endocrine gastrins have been implicated in the tumorigenic potential of colon cancer cells. In this article we focus on the role of endocrine and autocrine gastrins in colon cancer and review recent advances that suggest a role of processing intermediates of gastrin in colon carcinogenesis.

Journal Article↗

PubMed2000

Interactive software for generation and visualization of structured findings in radiology reports.

OBJECTIVE: Our objectives were to develop a user-friendly graphic interface for a module that integrates traditional radiology reporting, natural language processing, and editing capabilities; to facilitate the structuring of radiology reports as part of routine clinical practice; to use a commercial speech recognition module for online transcription; and to implement the module in a hardware-independent environment. CONCLUSION: After implementation, the module was tested with 150 chest radiology reports by two radiologists and assessed for ease of use and accuracy. Overall, accuracy was close to 90% and user satisfaction was high. When radiology reports are structured as a part of routine clinical practice, it is possible to accomplish intelligent indexing and retrieval to facilitate teaching and research.

Medical Records Systems, Computerized↗

PubMed2000

Evaluation of SNOMED3.5 in representing concepts in chest radiology reports: integration of a SNOMED mapper with a radiology reporting workstation.

Standardized medical terminologies are gaining importance in the representation of medical data. In this paper, we present the evaluation of the SNOMED3.5 medical terminology to code concepts routinely used in chest radiology reports. Integration of this terminology mapper into a radiology reporting workstation that incorporates a speech recognition system and a natural language processor is also discussed. A total of 700 anatomical location terms (including synonyms) were tested and 72% of the terms had corresponding SNOMED terms. Of the 28% that did not result in a match, 16% were either morphological variants of SNOMED terms or could be found from a combination of terms from two or more SNOMED axes. Only 12% of the terms (primarily specialized radiology terms) were concepts not actually included in the SNOMED terminology.

Humans↗

PubMed2000

Protection against leptospirosis by immunization with plasmid DNA encoding 33 kDa endoflagellin of L. interrogans serovar lai.

OBJECTIVE: To evaluate how the efficacy of DNA inocutation affects the ability to raise protective immunity against Leptospira. METHODS: A pair of oligonucleotide primers were designed to amplify the endoflagellar gene of L. interrogans sensu stricto serovar lai. An approximately 840bp fragment was generated with PCR and inserted into VR1012, a plasmid DNA expression vector, after the fragment and VR1012 were digested respectively with EcoRV and Sal I. A recombinant plasmid designated as VR1012+flaB2 was obtained. The vector, VR1012 consits of a pUC18 backbone with the cytomegalovirus (CMV) IE1 enhancer, promoter, and intron A, transcription regulatory elements and the BGH polyadenylation sequences driving the expressing of leptospiral endoflagellar gene of L. interrogans sensu stricto serovar lui. Plasmid encoding leptospiral endoflagellin gene was injected into quadriceps of NZW rabbits. RESULTS: This resulted in the generation of specific leptospiral antibody with high ELISA titer (1:32768) in the rabbits. Immuno/protection was performed in guinea pigs without adjuvant. The group "VR1012 + flaB2" showed higher survival rate (90%, 9/10 animals), compared with the group "VR1012 lack flaB2" and the group "normal saline". CONCLUSION: The technique of DNA vaccine has potential advantages over certain other vaccine preparation technologies. However whether DNA vaccine will be useful for vaccine development remains to be tested.

Animals↗

PubMed1999

Initial experiences with building a health care infrastructure based on Java and object-oriented database technology.

A multi-tiered telemedicine system based on Java and object-oriented database technology has yielded a number of practical insights and experiences on their effectiveness and suitability as implementation bases for a health care infrastructure. The advantages and drawbacks to their use, as seen within the context of the telemedicine system's development, are discussed. Overall, these technologies deliver on their early promise, with a few remaining issues that are due primarily to their relative newness.

Database Management Systems↗

PubMed1999

[Immunogenicity and immunoprotection of a leptospiral DNA vaccine].

Leptospirosis is one of the most widespread zoonosis. Immunization of NZW rabbit with plasmid DNA constructs encoding leptospiral endoflagellin can induce specific antibody response in the animal. The vector, VR1012 consists of a pUC18 backbone with the cytomegalovirus (CMV) IE1 enhancer, promoter, and intron A transcription regulatory elements and the BGH polyadenylation sequences driving the expression of leptospiral endoflagellar gene, flaB2. In this study, a pair of oligonucleotide primers were designed to amplify the endoflagellar of L. interrogans serovar lai. An approximately 840 bp fragment was generated with PCR and inserted into expressed plasmid vector, VR1012, after the fragment of VR1012 were digested respectively with EcoRV and Sall. A recombinant plasmid (designated VR1012 + flaB2) was obtained. Plasmid encoding leptospiral endoflagellin was injected into quadriceps of NZW rabbits. This resulted in the generation of specific leptospiral antibody with very high ELISA titer. Immunoprotection was performed in guinea pigs. The group "VR1012 + flaB2" had higher survival rate, compared with the group "VR1012 only" (control) and the group "Normal Saline only" (control). The result suggests that the technique of DNA injection should have an advantage over certain previous vaccine technologies.

Animals↗

PubMed1999

[Alignment of DNA sequences of ompL1 genes of insert fragment of recombinant plasmid, pDC38 of L. interrogans serovar lai and L. kirschneri].

In a previous study a genomic library of L. interrogans serovar lai was constructed by the present authors. Hybridization analysis (In situ, dot blot, Southern blot) with the DNA fragment containing OmpL1 (alpha-32P labeled) was performed. One of positive clones designated pDC38, was analyzed with 9 restriction enzymes (EcoRI, Bam HI, Hind III, Bgl, XbalI, ScaI, KpnI, PstI, Dra II). DNA hybridization was applied to analyze the homology of the recombinant fragment of ompL1 with the DNA of 18 strains of L. interrogans. The results showed that the homology of fragments of ompL1 were present in pathogenic Leptospira strains, but they were not in the non-pathogenic Leptospira biflexa strain Patoc I, Leptonema illini strain 3055. Therefore, Dr. David A. Haake performed the sequencing of pDC38. The results showed that pDC38 contained two inserts of 2.7 kb and 3.0 kb. The 3.0 insert contained a complete copy of the ompL1 gene. Dr. David A. Haake amplified the ompL1 gene using PCR primers specific for the ends of the gene and cloned the amplicon into pBluescript KS for sequencing. The alignment of complete DNA sequences of ompL1 of L. kirschneri and L. interrogans serovar lai showed the similarity of nucleotide sequences was 90%, variation was 10%. The derived amino acid sequence showed there was a high degree of amino acid sequence homology with ompL1 of L. kirschneri. These findings indicated that ompL1 gene was one of the important outer membrane protein genes in the L. interrogans serovar lai and using the probe pDC38 might provide a good tool for classification and identification of Leptospira.

Amino Acid Sequence↗

PubMed1998

Differential activation of IGF-II promoters P3 and P4 in Caco-2 cells during growth and differentiation.

BACKGROUND & AIMS: Insulin-like growth factor (IGF)-II gene is overexpressed in colon cancers. Transcriptional up-regulation may be the major mechanism contributing to its overexpression. IGF-II messenger RNA (mRNA) levels are up-regulated during proliferation followed by a significant decline during differentiation of Caco-2 cells. Mechanisms underlying transcriptional regulation of the IGF-II gene promoters (P1-P4) have yet to be examined in colon cancers, which was the basis for this study. METHODS: Ribonuclease protection assay was used to measure IGF-II mRNA derived from P1-P4. To determine if changes in the IGF-II transcripts reflected differences in promoter activity, transient transfection assays with the full-length P1-P4-luciferase expression vectors were performed. RESULTS: Both P3- and P4-derived transcripts were significantly up-regulated during the proliferative phase of the cells (days 3-6 in culture) and declined rapidly in cells undergoing differentiation (days 7-10); conversely, P1- and P2-derived transcripts were not detected. Similarly, transcriptional activity of P3 and P4 promoters reached peak levels by days 4-6 and declined rapidly thereafter. P1 and P2 were relatively inactive on all days. CONCLUSIONS: The activity of the P3 and P4 promoters may play a selective role in regulating IGF-II mRNA levels during growth and differentiation of colon cancer cells.

Caco-2 Cells↗

PubMed1998

Design and development of an interactive medical teleconsultation system over the World Wide Web.

The objective of the medical teleconsultation system presented in this paper is to demonstrate the use of the World Wide Web (WWW) for telemedicine and interactive medical information exchange. The system, which is developed based on Java, could provide several basic Java tools to fulfill the requirements of medical applications, including a file manager, data tool, bulletin board, and digital audio tool. The digital audio tool uses point-to-point structure to enable two physicians to communicate directly through voice. The others use multipoint structure. The file manager manages the medical images stored in the WWW information server, which come from a hospital database. The data tool supports cooperative operations on the medical data between the participating physicians. The bulletin board enables the users to discuss special cases by writing text on the board, send their personal or group diagnostic reports on the cases, and reorganize the reports and store them in its report file for later use. The system provides a hardware-independent platform for physicians to interact with one another as well as to access medical information over the WWW.

Internet↗

PubMed1998

[Immunoprotection in guinea pigs using DNA recombinant plasmid rpDJt and expressed protein P68 in L. interrogans serovar lai].

Immunoprotection against the infection by Leptospira interrogans serogroup Icterohemorrhagiae serovar lai strain 017 was demonstrated in guinea pigs vaccinated with DNA recombinant plasmid rpDJt and expressed protein P68 derived from genomic library of Leptospira strain 017. Thirty days after active immunization, each group received intraperitoneally (1/2 dose) and subcutaneously (1/2 dose) inoculum of L. interrogans serovar lai stain 017; cultures were adjusted to 5 x 10(8) cells/ml. All guinea pigs were observed for 10 days after challenge. Survival (%) of P68 group was 100(7/7); P23 group was 75(3/4); group rpDJt was 77(10/13); group lack recombinant (control) pT7-7 was 25 (3/12), and group with whole-cell inactivated vaccine was 93(13/14). Although the protective antigen in the leptospires has yet to be determined, it is evident that expressed protein P68 conferred a high degree of immunoprotection in guinea pigs.

Animals↗

PubMed1998

[Nucleotide sequence analysis of a species specific probe by an inserted fragment from recombinant plasmid pCX7 of L. interrogans sensu stricto serovar lai].

The etiological agents of leptospirosis are the pathogenic leptospires (L. interrogans sensu lato) which can be divided into 223 serovars organized into 23 serogroups. The serovar remains the basic taxon, but serotyping may now be accomplished and recognized by acceptable methods. Complementary molecular approaches are being used extensively to assess genetic relatedness amongst leptospires with restriction endonuclese analysis (REA), pulse field gel electrophoresis (PFGE) and DNA-DNA hybridization as well established tools. However, the method is cumbersome and unsuitable for routine application. To develop a sensitive and specific method for identification of pathogenic leptospires, a genomic library of L. interrogans sensu stricto serovar lai was constructed with the plasmid vector pUC9. A recombinant plasmid, designated pCX7 which has homologous fragment of pathogenic leptospires was screened from the bank. pCX7 could recognize pathogenic leptospiral DNA fragment 1.7 kb of strain 017 without cross hybridization to nonpathogenic leptospiral DNA. Inserted fragment of pCX7 DNA sequencing was performed by Dr. Yan Zhengxin (Max-Plank-Institut fur Biology, Tubingen, Germany). Insert fragment was cloned into pBluescript and sequenced by using ABI(Applied Bio. Systems, Model 373A). Nucleotide sequences were analyzed by Dr. Xiao Jianguo (Texas University Medical School and School of Public Health, Center for Infectious Diseases) using a suit of computer program (NIH). One open reading frame of 306 nucleotids were identified. There were identifiable initiation codons, terminators, pribnow box and sextama box within the sequenced regions. These results further confirmed that the little homology between L. interrogans sensu strito and L. borgpeterseni serovar javanica, L. inadai serovar ranarun and serovar manhao (L. genomospecies 2), L. biflexa serovar patoc, L. illini. pCX7 DNA probe could provide a base for identification and classification of leptospires.

DNA, Bacterial↗