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Biomedical subjects

Li Jiang

Publications and source records attributed to Li Jiang.

At least 109 records · Page 6Linked to original sources
PubMed2003

Amperometric determination of sulfide at a pre-oxidised nickel electrode in acidic media.

The electrochemical response of a pre-oxidised nickel electrode to increasing additions of sulfide has been examined and shown to produce a stripping-like voltammetric wave. A mechanism is described based on the formation of nickel sulfide at the electrode surface from a non-electroactive nickel oxide layer. The analytical utility of the approach has been examined and a linear range from 1 to 140 microM and a limit of detection of 0.8 microM is achievable, depending on the accumulation time.

Air Pollutants↗
PubMed2003

Physical adsorption of N,N'-diphenyl-p-phenylenediamine onto carbon particles: application to the detection of sulfide.

The derivatisation of carbon powder by physical adsorption of N,N'-diphenyl-p-phenylenediamine (DPPD) onto the surface of graphite particles (1-2 microm diameter) results in usefully functionalised carbon. The derivatised carbon powders have been studied using cyclic voltammetry by (i) abrasive immobilisation of the powder onto a basal plane pyrolytic graphite electrode (bppg) and (ii) by the manufacture of carbon-epoxy electrodes containing the derivatised carbon. The electrochemical response of the DPPD modified carbon has been examined in the presence of sulfide and possible reactions identified for the behaviour of each electrode substrate. The analytical application of the carbon-epoxy electrode for the sensing of sulfide is reported.

Journal Article↗
PubMed2003

Induction of hepatitis C virus-specific humoral and cellular immune responses in mice and rhesus by artificial multiple epitopes sequence.

The investigation of antigenic epitopes in hepatitis C virus (HCV) protein suggests that a central sequence combined with multiple antigenic epitopes of HCV might be significant as a potential vaccine candidate. This artificial sequence of combined and modified multiple antigenic epitopic peptides (Hc-B2), containing three B and four T cell epitopes, was constructed and expressed in E. coli. Antigen analysis indicated that this peptide antigen was capable of interacting with anti-sera collected from hepatitis C patients infected by three genotypes of HCV from three different geographic areas of China, respectively. The immunological analysis of this peptide antigen in mice and rhesus suggested that its immunogenicity was effective. However, a complete evaluation of this peptide could not be made as an effective animal model for HCV infection (such as in the chimpanzee) was not available for this study.

Amino Acid Sequence↗
PubMed2003

Automatic detection of small lung nodules on CT utilizing a local density maximum algorithm.

Increasingly, computed tomography (CT) offers higher resolution and faster acquisition times. This has resulted in the opportunity to detect small lung nodules, which may represent lung cancers at earlier and potentially more curable stages. However, in the current clinical practice, hundreds of such thin-sectional CT images are generated for each patient and are evaluated by a radiologist in the traditional sense of looking at each image in the axial mode. This results in the potential to miss small nodules and thus potentially miss a cancer. In this paper, we present a computerized method for automated identification of small lung nodules on multislice CT (MSCT) images. The method consists of three steps: (i) separation of the lungs from the other anatomic structures, (ii) detection of nodule candidates in the extracted lungs, and (iii) reduction of false-positives among the detected nodule candidates. A three-dimensional lung mask can be extracted by analyzing density histogram of volumetric chest images followed by a morphological operation. Higher density structures including nodules scattered throughout the lungs can be identified by using a local density maximum algorithm. Information about nodules such as size and compact shape are then incorporated into the algorithm to reduce the detected nodule candidates which are not likely to be nodules. The method was applied to the detection of computer simulated small lung nodules (2 to 7 mm in diameter) and achieved a sensitivity of 84.2% with, on average, five false-positive results per scan. The preliminary results demonstrate the potential of this technique for assisting the detection of small nodules from chest MSCT images.

Algorithms↗
PubMed2003

Somatic mutation analysis of p53 and ST7 tumor suppressor genes in gastric carcinoma by DHPLC.

AIM: To verify the effectiveness of denaturing high-performance liquid chromatography (DHPLC) in detecting somatic mutation of p53 gene in gastric carcinoma tissues. The superiority of this method has been proved in the detection of germline mutations, but it was not very affirmative with respect to somatic mutations in tumor specimens. ST7 gene, a candidate tumor suppressor gene identified recently at human chromosome 7q31.1, was also detected because LOH at this site has also been widely reported in stomach cancer. METHODS: DNA was extracted from 39 cases of surgical gastric carcinoma specimen and their correspondent normal mucosa. Seven fragments spanning the 11 exons were used to detect the mutation of p53 gene and the four exons reported to have mutations in ST7 gene were amplified by PCR and directly analyzed by DHPLC without mixing with wild-type allele. RESULTS: In the analysis of p53 gene mutation, 9 aberrant DHPLC chromatographies were found in tumor tissues, while their normal-adjacent counterparts running in parallel showed a normal shape. Subsequent sequencing revealed nine sequence variations, 1 polymorphism and 8 mutations including 3 mutations not reported before. The mutation rate of p53 gene (21%) was consistent with that previously reported. Furthermore, no additional aberrant chromatography was found when wild-type DNA was added into the DNA of other 30 tumor samples that showed normal shapes previously. The positivity of p53 mutations was significantly higher in intestinal-type carcinomas (40%) than that in diffuse-type (8.33%) carcinomas of the stomach. No mutation of ST7 gene was found. CONCLUSION: DHPLC is a very convenient method for the detection of somatic mutations in gastric carcinoma. The amount of wild type alleles supplied by the non-tumorous cells in gastric tumor specimens is enough to form heteroduplex with mutant alleles for DHPLC detection. ST7 gene may not be the target gene of inactivation at 7q31 site in gastric carcinoma.

Base Sequence↗
PubMed2003

Cloning and sequence analysis of Bacillus thuringiensis gene fragments isolated by restriction digest PCR.

OBJECTIVE: To clone and analyze Bacillus thuringiensis gene fragments isolated by restriction digest PCR (RD-PCR). METHOD: Specific primers were designed to amplify the genes of Bacillus thuringiensis israelensis (Bti), and the PCR products were classified and re-amplified by RD-PCR to obtain the fragments for subsequent purification and cloning into the pMD18-T vectors, followed by rapid identification. The recombinant plasmids were extracted from positive clones and the target gene fragments were sequenced. RESULTS: Sequence analysis showed that all the fragments amplified were Bti genes. CONCLUSION: RD-PCR is reliable in breaking down large gene fragments into confined and shorter gene fragments for preparing microarray probes.

Bacillus thuringiensis↗
PubMed2003

[Genomic variations in the locus for aminopeptidase N:a putative cellular receptor for SARS-CoV spike glycoprotein].

Aminopeptidase N has been identified as the cellular receptor for human coronavirus HCoV-229E and was a putative receptor for the spike glycoprotein encoded by the SARS-associated coronavirus (SARS-CoV). We report here identification of 9 single nucleotide polymorphisms (SNPs) in ANPEP, encoding human aminopeptidase N, in Chinese. All ANPEP exons and their flanking intronic sequences were amplified from unrelated normal individuals by polymerase chain reaction (PCR) and screened using denaturing high-performance liquid chromatography (DHPLC). Nine SNPs were revealed after direct sequencing of PCR amplified fragments which showed changes of DHPLC chromatogram. Four of these polymorphisms, T321M(962C > T), S651L(1952C > T), S752N(2255G > A) and G764R(2290G > A), were non-synonymous; the remaining exonic synonymous and intronic ones were T795T(2385C > T), IVS7 + 17G > A, IVS14-16A > G, IVS17 + 12C > G and IVS17 + 44C > T. Our data may be useful for studies to investigate the role of host genetic factors in SARS pathogenesis, especially for identifying SARS-susceptible and/or anti-SARS alleles.

Animals↗
PubMed2003

[Neuroprotective effects of Astragulus membranaceus on hypoxia-ischemia brain damage in neonatal rat hippocampus].

OBJECTIVE: To study neuroprotective effects of astragulus membraneaceus on a neonatal rat hippocampus of hypoxia-ischemia brain damage (HIBD). METHOD: The neonatal hypoxia-ischemia model was established with 7-day-old rat pups. Brain injury was examined by neuron death rate in the hippocampal CA1 area. Caspase-3 (cysteinyl aspartate-specific proteinase) mRNA expression in ipsilateral hippocampal was measured by half-quantitative reverse transcription and polymerization chain reaction (RT-PCR). 90-day-old rats were used in tri-equal-arm maze to observe discrimination learning ability. Sham, model and astragulus-membraneaceus treated groups were set up. RESULT: In model group, caspase-3 mRNA showed an increase at 6h, with maximum arrivimg at 24 h - 48 h after HI. In astragulus-membraneaceus treated group, neurons death rate and caspase-3 mRNA were significantly reduced by astragulus membraneaceus, and discrimination learning ability of developed rats were improved obviously. CONCLUSION: Astragulus membraneaceus has a strong protective effect on neuronal damage in the immature rat hippocampus, which is ralated reducing caspase-3 expression.

Animals↗
PubMed2003

[Analysis and mapping of a rice repeated sequence].

A repeated sequence with a length of 560 bp, termed as DH17, was obtained during PCR amplification of rice NBS-LRR homologues. A repeated unit of 352 bp in the DH17 fragment was revealed through sequence analysis and comparison, which has a high homology with the known sequences of OS48 and TrsA, and belongs to the same repeat family. Southern hybridization displayed that there are higher DH17 copies in the genome of an indica variety, ZYQ8,than that in the genome of japonica variety, JX17. The tandom repeated DH17 sequence was mapped on the long arm end of chromosome 12 through RFLP analysis of a double haploid population derived from ZYQ8 and JX17 using DH17 as a probe.

English Abstract↗
PubMed2002

Intercellular calcium signaling mediated by point-source burst release of ATP.

Calcium signaling, manifested as intercellular waves of rising cytosolic calcium, is, in many cell types, the result of calcium-induced secretion of ATP and activation of purinergic receptors. The mechanism by which ATP is released has hitherto not been established. Here, we show by real-time bioluminescence imaging that ATP efflux is not uniform across a field of cells but is restricted to brief, abrupt point-source bursts. The ATP bursts emanate from single cells and manifest the transient opening of nonselective membrane channels, which admits fluorescent indicators of < or = 1.5 kDa. These observations challenge the existence of regenerative ATP release, because ATP efflux is finite and restricted to a point source. Transient efflux of cytosolic nucleotides from a subset of cells may represent a conserved pathway for coordinating local activity of electrically nonexcitable cells, because identical patterns of ATP release were identified in human astrocytes, endothelial cells, and bronchial epithelial cells.

Adenosine Triphosphate↗
PubMed2002

Connexin 43 enhances the adhesivity and mediates the invasion of malignant glioma cells.

A hallmark of astrocytic tumors is their infiltrative nature. Although their aggressive and typically widespread dispersal in the adult brain differs fundamentally from that of other brain tumors, little is known about their cellular basis. Astrocytic tumors express the gap junction protein connexin 43 (Cx43), and we show here that Cx43 expression induced the morphological transformation of glioma cells into an epithelial phenotype. In a short-term aggregation assay, Cx43 expression was associated with a several-fold increase in the competence of glioma cells to aggregate. Antibodies directed against the extracellular domain of Cx43 restored the connexin-deficient phenotype, as manifested by a dose-dependent reduction in aggregation. Apart from their role in gap junction formation, connexins may therefore be considered a distinct class of membrane proteins with adhesive properties. Moreover, implanted Cx43-expressing glioma cells established functional gap junction channels with host astrocytes and dispersed through a substantially greater volume of brain parenchyma than mock- and mutant Cx43-transfected sister cells. Cx43 expression therefore may modulate not only the adhesion of astrocytes to one another, but the spread of glial tumor cells throughout astrocytic syncytia. These observations widen our concept of the potential interactions between tumor cells and their surroundings and suggest that both connexin proteins and their derived gap junctions are critical determinants of the invasiveness of central gliomas.

Animals↗
PubMed2002

[Relationship between interleukin-1B and interleukin-1 receptor antagonist gene polymorphisms and susceptibility to gastric cancer].

OBJECTIVE: To investigate the polymorphisms of interleukin-1B (IL-1B) promotor region 31 C/T and interleukin-1 receptor antagonist (IL-1RN) gene and the relationship between the genotype of IL-1 and IL-1RN and susceptibility to gastric cancer in Chinese population. METHODS: Genomic DNA was extracted from the juxta-cancerous normal mucosal biopsies of 50 patients with gastric cancer taken by endoscopy and from the peripheral lymphocytes of 50 normal controls and then was subjected to PCR amplification. The PCR product was digested by restriction endonuclease Alu I. The product of digestion was subjected to 2% agarose gel electrophoresis and ethidium bromide staining. RESULTS: The IL-1B -31C allele was detected in 75% of normal controls and 53% of patients, while the IL-1B -31T allele was detected in 25% of normal controls and 47% of patients. The frequency of -31C/-31C was 56% (28/56) and 30% (15/50) in normal controls and patients respectively. The frequency of -31C/-31T was 38% (19/56) and 46% (23/50) in normal controls and patients respectively. The frequency of -31T/-31T was 6% (3/56) and 24% (12/50) in normal controls and patients respectively. IL-1B -31T carriers were at increased risk of gastric cancer with an odds ratio of 7.5 for -31T/-31T homozygotes (95% CI, 2.0 approximately 27.6) and of 2.3 for -31C/-31T (95% CI, 0.9 approximately 5.4) respectively. Only three of the five kinds of polymorphism of IL-1RN (1/1, 1/2 and 2/2) were found in this study. The frequency of 1/1 was 54% (27/50) and 24% (12/50) in normal controls and patients respectively. The frequency of 1/2 was 38% (19/50) and 50% (25/50) in normal controls and patients respectively. The frequency of 2/2 was 8% (4/50) and 26% (13/50) in normal controls and patients respectively. The IL-1RN * 1 allele was detected in 73% of normal controls and 49% of patients; while the IL-1RN * 2 allele was detected in 27% of normal controls and 51% of patients. IL-RN * 2 carriers were at increased risk of gastric cancer with an odds ratio of 7.31 for 2/2 homozygotes (95% CI 2.13 approximately 25.09) and of 2.96for 1/2 heterozygotes (95% CI 1.22 approximately 7.21), respectively. CONCLUSION: The polymorphism of promotor region -31C/T of IL-1B gene and the polymorphism of IL-1RN genes 1/2 and 2/2 are associated with the susceptibility of gastric cancer in Chinese. Carrying -31T allele increases the risk of gastric cancer. Polymorphism of IL-1RN and IL-1B gene may be used as indicators of susceptibility of gastric carcinogenesis.

Alleles↗
PubMed2002

An SR-protein induced by HSVI binding to cells functioning as a splicing inhibitor of viral pre-mRNA.

The interaction between a virus and its specific receptor on the membrane of the host cell mimics the physiological combination of signal ligand and its receptor, and initiates the specific signal transduction from this activated receptor to induce a relative gene response. During the investigation of the interaction between Herpes simplex virus I (HSVI) and human fibroblast via the virus binding to its receptor complex on the cellular membrane, a new gene of cellular response against the specific stimulation of HSVI binding to fibroblasts was cloned from a cDNA library established from mRNA of an early gene response. This gene encoded a protein of 14.9kDa with the structural characteristics of Arg-rich and RS repeats. The analysis of the role of this protein in the infection by HSVI indicated that this protein, expressed only in G(1)/S phase and phosphorylated, functioned as a splicing inhibitor of HSVI pre-mRNA. The details of the mechanism of this inhibition of HSVI pre-mRNA splicing is still unclear.

Amino Acid Sequence↗
PubMed2002

[Protein microarrays and their medical applications].

The microarrays have revolutionised biomedical experimentation and diagnostics, enabling ordered high throughput analysis. During the past decade, classic solid phase substrates, such as microlitre plates, membrane filters and microscopic slides, were turn into high-density, chip-like structure. The concept of the arrayed library was central to this development which now extends from DNA to protein. The availability of such protein microarrays would facilitate the simultaneous analysis of thousands of interactions within a single experiment. They can be utilized for massively parallel testing of protein function or recognized their target polypeptide in complex biological solution. This article will focus on the current strategies used to generate protein microarray and their applications in biological research, medicine and diagnostics.

Biomedical Research↗
PubMed2002

Application of restriction display PCR in preparing the probes of the gene chip for investigating gene expression profile of K562 cells.

OBJECTIVE: To collect the gene fragments of the gene chips for investigating the expression profile of K562 cells. METHODS: The mRNA was extracted from cultured K562 cells to obtain cDNA by reverse transcription-PCR. The gene fragment products of different groups were acquired and isolated by reverse display PCR (RD-PCR). RESULT: The probes for the gene chip were successfully prepared. CONCLUSION: RD-PCR adapted in this study suits the needs for collecting the probes for the gene chips.

DNA Probes↗
PubMed2002

Endothelial NO synthase gene expression in experimental vasospasm in rabbits.

OBJECTIVE: To investigate the relationship between endothelial NO synthase (eNOS) gene expression and experimental vasospasm. METHODS: Sixteen rabbits were randomly divided into 2 groups, which were subjected to balloon endothelial denudation with normal diet (n=8) or with hypercholesterol diet group (n=8). Angiography was performed to detect the vasospasm induced by ergonovine before and after denudation and 8 weeks after hypercholesterol feeding. In situ hybridization and Northern blotting were performed to localize and quantitate respectively the expression of eNOS mRNA. RESULTS: Visible vasospasm was induced at the denuded sites in rabbits with hypercholesterol diet, in which the expression of eNOS mRNA was detected in the endothelium by in situ hybridization at a lower level than that of rabbits with normal diet, as demonstrated by Northern blotting. CONCLUSION: The decrement of eNOS mRNA expression resulted from balloon endothelial denudation and hypercholesterolemia may play an important role in the pathogenesis of experimental vasospasm.

Animals↗
PubMed2002

[Construction and expression of mouse DOC-1R antisense gene vector].

BACKGROUND & OBJECTIVE: DOC-1R gene is a candidate tumor suppressor gene that when connected specifically with CDK2 can control the course of cell cycle by restraining the reciprocity of CDK2 and cyclin. The aim of this study was to construct the antisense DOC-1R plasmid and to investigate the effect of DOR-1R gene on the growth of normal cell. METHOD: The recombinant antisense plasmid was constructed after screening the expression of DOC-1R gene. Following transfection, the effect of DOC-1R on cell growth was determined by assessing the ability of cell replication and observing soft agar culture. RESULT: The growth speed of NIH3T3 transfected by mouse DOC-1R gene was of significant difference from that transfected by empty vector. The pcDNA3-DOC-1R+ vector significantly inhibited the cell replication, while the pcDNA3-DOC-1R- vector stimulated the cell replication. In soft agar culture, the colony formation capacity was decreased in the recombinant sense vector group. The clone formation rate was decreased and the size of the colony formed was smaller as well. In contrast, the colony forming ability was remarkably increased in the antisense vector group. The clone formation rate was increased significantly, compared to that in the sense group. CONCLUSION: Mouse DOC-1R gene can significantly inhibit cell growth and colony formation capacity. It will be helpful for the study on the mechanism of normal cell growth and replication as well as for research in tumor treatment and prevention.

3T3 Cells↗