Biomedical subjects

Li Jiang

Publications and source records attributed to Li Jiang.

At least 91 records · Page 5Linked to original sources

PubMed2004

Expression of survivin in primary and metastatic gastric cancer cells obtained by laser capture microdissection.

AIM: Survivin, a recently identified member of the inhibitor of apoptosis protein family, is expressed during development and in various human cancers. However, its expression in normal tissues and clinical relevance in cancers are still debated. In the present study, we analyzed the expression of the survivin gene in human primary and metastatic gastric cancer cells as well as in paired epithelial cells from normal gastric mucosa by means of a novel laser capture microdissection (LCM) technique coupled with reverse transcription-polymerase chain reaction (RT-PCR). METHODS: Thirty patients who had undergone gastrectomy with lymph node dissection for gastric cancer without preoperative treatments were included. Neoplastic tissue, metastatic lymph nodes, and apparently uninvolved normal tissue were collected from each patient. LCM-captured "pure" cell groups were respectively subjected to RT-PCR analysis with primers specific for the survivin gene. RESULTS: Of the paired samples from 30 gastric cancer patients studied, 24 (80%) primary gastric cancer cell groups and 7 (23%) adjacent morphologically "normal" gastric epithelial cell groups were shown to have a detectable survivin expression. There was a statistically significant difference in suvivin expression between these two groups (P<0.01). Meanwhile, 95% (19/20) of the metastatic gastric cancer cell groups from lymph nodes had a clear expression of te survivin gene. However, no significant correlation between survivin expression and clinicopathological features of gastric cancer was observed in the present study. CONCLUSION: Survivin expression is present in the majority of gastric cancer cell groups obtained by LCM techniques. The high expression rate in metastatic lesions suggests a possible role of survivin in cancer invasiveness and metastasis. It may contribute to the detection of gastric cancer micrometastasis as a potential molecular marker. In addition, the high expression percentage renders survivin a potential target in the therapy for gastric cancer.

Adult↗

PubMed2004

Abrasively immobilised multiwalled carbon nanotube agglomerates: a novel electrode material approach for the analytical sensing of pH.

We demonstrate for the first time that agglomerates of multiwalled carbon nanotubes (MWCNTs) can be formed in which the binder in the agglomerate is itself a redox-active molecular solid. Two separate agglomerates were formed by dissolving 9,10-phenanthraquinone (PAQ) or 1,2-napthaquinone (NQ) in acetone together with MWCNTs and adding an excess of aqueous solution to cause precipitation of agglomerates, approximately 10 microns in dimension, which consist of bundles of nanotubes running into and throughout the amorphous molecular solid that binds the agglomerate together. The nature of this structure, when immobilised on a substrate electrode and in contact with aqueous electrolyte solutions, gives rise to many three-phase boundaries, electrolyte|agglomerate|conductor, which is advantageous to the solid-state analytical electrochemistry of such a material as it imparts a larger electroactive surface area than other modified carbon electrodes. The two agglomerates each gave a voltammetrically measurable response to changes in pH; when abrasively immobilised on a basal plane pyrolitic graphite electrode a plot of peak potential against pH produced a linear response for both MWCNT-PAQ and MWCNT-NQ agglomerates over the pH range pH 1-12 and over the temperature range 20-70 degrees C.

Chemistry, Physical↗

PubMed2004

Effect of cyclin G2 on proliferative ability of SGC-7901 cell.

AIM: To study the effect of cyclin G2 on proliferation of gastric adenocarcinoma cell line-SGC-7901 cell in vitro. METHODS: By use of cation lipofectamine transfection reagent, the pIRES-G2 and pIRESneo plasmids were transferred into SGC-7901cell line. Anticlones were selected by G418. Positive clones were observed and counted using Giemsa staining. Cell proliferative ability was assayed by MTT. RESULTS: (1) The clone number of pIRES-G2 group decreased, clone volume reduced. The number of cell clones in pIRESneo group was 87+/-3, that of pIRES-G2 group was 53+/-4, occupying 60.1% of pIRESneo group, there was significant difference obviously (P<0.01, t=15.45). (2) The average absorbance of clone cell obtained by stable transfection of pIRES-G2 at 570 nm was 1.6966+/-0.2125, the average absorbance of clone cell obtained by stable transfection of pIRESneo at 570 nm was 2.1182+/-0.3675, there was significant difference between them (P<0.01, t=3.412). CONCLUSION: Cyclin G2 can inhibit SGC-7901cell proliferative ability obviously, it may be a negative regulator in cell cycle regulation.

Adenocarcinoma↗

PubMed2004

Vascular development in the retina and inner ear: control by Norrin and Frizzled-4, a high-affinity ligand-receptor pair.

Incomplete retinal vascularization occurs in both Norrie disease and familial exudative vitreoretinopathy (FEVR). Norrin, the protein product of the Norrie disease gene, is a secreted protein of unknown biochemical function. One form of FEVR is caused by defects in Frizzled-4 (Fz4), a presumptive Wnt receptor. We show here that Norrin and Fz4 function as a ligand-receptor pair based on (1) the similarity in vascular phenotypes caused by Norrin and Fz4 mutations in humans and mice, (2) the specificity and high affinity of Norrin-Fz4 binding, (3) the high efficiency with which Norrin induces Fz4- and Lrp-dependent activation of the classical Wnt pathway, and (4) the signaling defects displayed by disease-associated variants of Norrin and Fz4. These data define a Norrin-Fz4 signaling system that plays a central role in vascular development in the eye and ear, and they indicate that ligands unrelated to Wnts can act through Fz receptors.

Animals↗

PubMed2004

Mutations in LRP5 or FZD4 underlie the common familial exudative vitreoretinopathy locus on chromosome 11q.

Familial exudative vitreoretinopathy (FEVR) is an inherited blinding disorder of the retinal vascular system. Autosomal dominant FEVR is genetically heterogeneous, but its principal locus, EVR1, is on chromosome 11q13-q23. The gene encoding the Wnt receptor frizzled-4 (FZD4) was recently reported to be the EVR1 gene, but our mutation screen revealed fewer patients harboring mutations than expected. Here, we describe mutations in a second gene at the EVR1 locus, low-density-lipoprotein receptor-related protein 5 (LRP5), a Wnt coreceptor. This finding further underlines the significance of Wnt signaling in the vascularization of the eye and highlights the potential dangers of using multiple families to refine genetic intervals in gene-identification studies.

Amino Acid Sequence↗

PubMed2004

Presynaptic inactivation of action potentials and postsynaptic inhibition of GABAA currents contribute to KA-induced disinhibition in CA1 pyramidal neurons.

Kainate-type glutamate ionotropic receptors (KAR) mediate either depression or potentiation of inhibitory transmission. The mechanisms underlying the depressant effect of KAR agonists have been controversial. Under dual patch-clamp recording techniques in synaptically coupled pairs of CA1 interneurons and pyramidal neurons in hippocampal slices, micromolar concentrations of KAR agonists, kainic acid (KA, 10 microM) and ATPA (10 microM), induced inactivation of action potentials (APs) in 58 and 50% of presynaptic interneurons, respectively. Inactivation of interneuronal APs might have significantly contributed to KA-induced decreases in evoked inhibitory postsynaptic currents (eIPSCs) that are obtained by stimulating the stratum radiatum. With controlled interneuronal APs, KAR agonists induced a decrease in the potency (mean amplitude of successful events) and mean amplitude (including failures) of unitary inhibitory postsynaptic currents (uIPSCs) without significantly changing the success rate (P(s)) at perisomatic high-P(s) synapses. In contrast, KAR agonists induced a decrease in both the P(s) and potency of uIPSCs at dendritic high-P(s) synapses. KAR agonists induced an inhibition of GABA(A) currents by activating postsynaptic KARs in pyramidal neurons; this was more prominent at dendrites than at soma. Both the exogenous GABA-induced current and the amplitude of miniature IPSCs (mIPSCs) were attenuated by KAR agonists. Thus the postsynaptic KAR-mediated inhibition of GABA(A) currents may contribute to the KAR agonist-induced decrease in the potency of uIPSCs and KA-induced disinhibition.

Action Potentials↗

PubMed2004

[Western blotting analysis of specific antigens from different components of Echinococcus metacestodes].

OBJECTIVE: To analyze antigens for searching specific antigenic components for immunodiagnosis of echinococcosis. METHODS: Fourteen crude antigens from different tissues (cyst fluid, protoscoleces, laminated layer and germinal layer) of Echinococcus granulosus and E. multilocularis metacestodes and other 4 species of cestodes were analyzed by Western blotting. The differences of protein bands were compared for the 14 crude antigens by reacting with pooled sera from cystic echinococcosis (CE) and alveolar echinococcosis (AE) patients. RESULTS: Eleven protein bands from the antigens reacted nonspecifically with sera from both CE and AE patients were Mr 130000, 100000, 94000, 80000, 75000, 66000, 62000, 52000, 38000, 32000, 24000. The highly specific protein bands recognized by AE sera were Mr 120000, 109000, 86000, 59000, 43000, 28000, 20000, 18000, and by CE sera were Mr 41000, 40000, 22000, 16000 and 12000. CONCLUSION: Different antigens shared by the two species of Echinococcus were examined and potential antigenic proteins specific for AE or CE sera were found, providing useful information for further identifying specific antigens for immunodiagnosis.

Animals↗

PubMed2004

A novel RDS/peripherin gene mutation associated with diverse macular phenotypes.

Pattern dystrophy is a heterogeneous group of retinal dystrophies of which butterfly-shaped pattern dystrophy (BPD) and adult-onset foveomacular dystrophy (AOFMD) are the two most common forms. BPD is characterized by a butterfly-shaped, irregular, depigmented lesion at the level of the retinal pigment epithelium. In contrast, AOFMD is characterized by the presence of slightly elevated, symmetric, solitary, round to oval, yellow lesions at the level of the retinal pigment epithelium. We identified three independent kindreds with pattern dystrophy, one with four patients affected with BPD and the other two with 14 affected patients with AOFMD. We performed complete ophthalmic examination, fluorescein angiography, linkage mapping, and mutational screening in the RDS/peripherin gene in the affected patients. Patients affected with BPD had a best-corrected vision of 20/20 to 20/25, whereas vision in the eyes of patients with AOFMD ranged from 20/20 to 20/400. In all three kindreds, sequence analysis identified an A-to-G change at nucleotide position 422 of the RDS/peripherin gene, predicting a novel Tyr-141-Cys substitution. A haplotype analysis revealed that these three kindreds shared an identical disease haplotype at the RDS/peripherin locus, indicating that the mutation reflects a founder effect. The sequence change that segregated with the disease phenotype was not observed in 200 control chromosomes. Our results identified a novel mutation in the RDS/ peripherin gene that can cause diverse macular phenotypes. Genetic and clinical investigation of pattern dystrophy may provide useful diagnostic tools and new treatment strategies for this disorder.

Adult↗

PubMed2004

Novel mutations of the RNA-specific adenosine deaminase gene (DSRAD) in Chinese families with dyschromatosis symmetrica hereditaria.

Dyschromatosis symmetrica hereditaria (DSH) is an autosomal dominant skin disorder. It is also called "reticulate acropigmentation of Dohi" or "symmetric dyschromatosis of the extremities". The DSH locus has recently been mapped to chromosome 1q21 and pathogenic mutations were identified in the DSRAD gene encoding double-stranded RNA-specific adenosine deaminase in Japanese patients with DSH. We report here two novel point mutations, Q513X(1537C>T) and R916W(2746C>T) in the DSRAD gene identified in two Chinese families, respectively. These data suggest that mutations in DSRAD were also associated with DSH in Chinese. This is the first report on DSRAD as the causative gene of DSH in the Chinese population.

Adenosine Deaminase↗

PubMed2004

[The expression and activity detection of a variant N protein of SARS-CoV].

AIM: To construct an expression vector pGEX-2T/N, and to express the fusion protein consisting of N protein of SARS-CoV and GST in E.coli. METHODS: The N region gene of SARS-CoV was cloned by RT-PCR. The expression vector was constructed by DNA recombination. The recombinant plasmid was transformed into E.coli BL21(DE3). The expression of the fusion protein was detected by Western blot. RESULTS: (1) As compared with the sequences in GenBank, 20 bp were deleted in DNA sequence of the cloned N protein. (2) The fusion protein GST-N was soluble. Western blot analysis showed that the reaction of GST-N to anti-SARS-CoV sera was positive. CONCLUSION: The pGEX-2T/N has been constructed and expressed in the form of fusion protein GST-N successfully, which lays the foundation for further study of SARS-CoV N protein.

Base Sequence↗

PubMed2004

[Long-term outcomes after elective coronary stenting in diabetic patients].

OBJECTIVE: To observe the long-term outcomes following coronary stenting in diabetic patients with coronary artery disease. METHODS: This cohort study comprised 808 consecutive patients with coronary artery disease who underwent elective coronary stenting, including 174 diabetic patients and 634 non-diabetic patients. The long-term follow-up outcomes were compared. RESULTS: Procedural success rate was similar (96.0% vs 96.1%). Follow-up rate was 95.3%. Mean follow-up duration was (19 +/- 7.8) months (ranged from 6 to 42 months). Compared with non-diabetic patients, diabetic patients had less improvement of cardiac function (52.2% vs 61.0%), more re-admission (42.7% vs 32.5%), and higher occurrence rates of major adverse cardiac events (30.6% vs 22.2%), angiographic restenosis rate (19.1% vs 12.5%) and mortality (10.2% vs 4.6%). Logistic regression analysis indicated that diabetes mellitus was an independent predicator of death (odd ratio 2.20, 95% CI 1.12 approximately 4.33, P = 0.022) and restenosis (odd ratio 1.66, 95% CI 1.04 approximately 2.67, P = 0.035). CONCLUSION: Diabetic patients undergoing elective coronary stenting have acceptable long-term outcomes, but diabetes mellitus is still independently associated with worse late prognosis.

Aged↗

PubMed2004

Expression of survivin mRNA in peritoneal lavage fluid from patients with gastric carcinoma.

BACKGROUND: Peritoneal dissemination is the most common pattern of metastasis in advanced gastric carcinoma with serosal invasion. In the present study, we reported the clinical relevance of a new diagnostic method involving RT-PCR, using survivin as the target gene, for the detection of free cancer cells in peritoneal washes. METHODS: Intraoperative peritoneal washes were obtained from 48 patients who underwent surgery for gastric cancer. RT-PCR analysis with primers specific for survivin and conventional cytological examinations were both performed. RESULTS: Survivin mRNA was not detected in any peritoneal wash samples from patients with benign disease, but was detected in 28 of 48 samples taken from patients with gastric cancer and in all metastatic nodules. Survivin expression in the peritoneal cavity significantly correlated with depth of cancer invasion, lymph node metastasis, and TNM stage. There were 92% of clinically evident peritoneal metastasis cases showed detectable survivin expression. The combination of survivin RT-PCR and cytological examination yielded positive results in 66.7% (32/48) of patients with gastric cancer, much higher than the results produced by cytological method alone. CONCLUSIONS: Survivin mRNA detected in peritoneal lavage fluid might indicate the presence of free cancer cells in the peritoneal cavity. The high sensitivity of the RT-PCR-based survivin assay suggests that survivin serves as a molecular marker for detecting peritoneal micrometastasis. Its ubiquitous expression in peritoneal cancer cells and metastatic nodules also suggests a promising future therapeutic strategy based on survivin inhibition for cases of gastric cancer involving peritoneal metastasis.

Adult↗

PubMed2004

Preliminary analysis of CDK2 sequence and its nuclear import.

We constructed the plasmids encoding enhanced green fluorescent protein (EGFP)-tagged wild type cyclin-dependent kinase 2(CDK2) (pEGFP-CDK2) and CDK2 deletion mutants (pEGFP-CDK2N and pEGFP-CDK2C, lacking the last C-terminal and the first N-terminal 97 amino acids of CDK2, respectively) and transfected them into HeLa cell line and CHO cell line. After synchronization, green fluorescent signals were detected mainly in nucleus of the cells transfected with pEGFP-CDK2 and predominantly in cytoplasm of the cells transfected with the two mutant CDK2 constructs. Our results suggested that there were no nuclear-import signals in CDK2 and that CDK2 nuclear import might be mediated by association with other proteins through the three-dimensional structure formed by amino acids including those from the N- and C-terminal regions of CDK2.

Active Transport, Cell Nucleus↗

PubMed2004

[Gene cloning, expression and serological evaluation of diagnostic antigen Em18 for alveolar echinococcosis].

OBJECTIVE: To clone, express and serologically evaluate the Em18 antigen gene of Echinococcus multilocularis for diagnostic purpose. METHODS: Polymerase chain reaction (PCR) was employed for amplification of the target gene fragments which was then ligated with pET28a+ vector. The constructed plasmid was transferred into E. coli BL21 (DE3) for expression. The recombinant proteins were purified with Ni-NTA agarose by affinity chromatography. 237 sera were used for evaluating diagnostic value of the recombinant Em18 antigen. RESULTS: Two high-level expression clones (designated as ReEm18-1 and ReEm18-2) were obtained. ReEm18-1 showed the expected sequence, ReEm18-2 showed the same sequence but with 27 nucleotides deletion. The molecular weight of the two expression proteins was Mr 28,000 and 26,000, respectively. Serological evaluation by ELISA was carried out using sera from 101 patients with alveolar echinococcosis (AE), 47 with cystic echinococcosis (CE), 30 with cysticercosis (CC), 10 with hepatic cancer (HC), 9 with schistosomiasis (Sj) and 40 from healthy persons (NH) from both endemic and non-endemic areas. The results showed an overall sensitivity of 86.1% and 90.1% with ReEm18-1 and ReEm18-2 for AE sera, specificity 93.4% and 94.1%, positive predictive value 90.6% and 91.9%, negative predictive value 90.1% and 92.8% and efficiency 90.3% and 92.4%, respectively. The correlation analysis between the size of AE lesions and the serum absorbance reacted with recombinant Em18 antigens showed that there was a positive correlation between antibody level and the course of the disease. CONCLUSION: ReEm18 antigens are specific for AE diagnosis, and the serum antibody level displays a good correlation with the course of the disease at early stage. Similar results achieved by both ReEm18-1 and ReEm18-2 antigens.

Animals↗

PubMed2003

A thin-layer amperometric sensor for hydrogen sulfide: the use of microelectrodes to achieve a membrane-independent response for Clark-type sensors.

An electrochemical cell design of the Clark type including a thin layer of electrolyte in contact with a microelectrode has been successfully applied for the determination of sulfide utilizing its electrochemically initiated reaction with aqueous diethyl-p-phenylenediamine. The analytical parameters obtained were independent of the membrane used to separate the inner chamber and the outside sulfide-containing solution. The independence arises since the thickness of the diffusion layer associated with the microelectrode is small and, in contrast to the conventional macroelectrode Clark electrode, does not impinge on the membrane. This provides an improvement in gas sensor design and development as it obviates the need for membrane calibration and should simplify the application of Clark cells for variable-temperature measurements.

Electrochemistry↗

PubMed2003

Voltammetric characterization of a N,N'-diphenyl-p-phenylenediamine-loaded screen-printed electrode: a disposable sensor for hydrogen sulfide.

The voltammetric response of a 10% (by weight) N,N'-diphenyl-p-phenylenediamine (DPPD) and 90% (by weight) carbon and binder screen-printed electrode has been examined in aqueous media over a range of pH using cyclic voltammetry both in the presence and in the absence of sulfide. In the absence, the screen-printed electrode undergoes an initial oxidative process on the surface of the solid organic particles to form an insoluble layer of the corresponding cation radical salt, DPPD(*)(+)X(-), where X(-) is an anion present in the solution. The charge transfer is thought to occur at the three-phase boundary between solid DPPD, carbon, and the aqueous solution. At higher potentials, a second oxidative wave is observed that is attributed to the oxidation of the bulk DPPD with intercalation of the anion species present to form a solid phase of DPPD(*)(+)X(-). The two voltammetric processes were found to stabilize after repetitive scanning, after which time, sulfide was added to the solution. The voltammetric response was found to respond to sulfide by showing a decrease in both the oxidative and reductive waves, which can be attributed to the sulfide effectively blocking the three-phase boundary. The response was found to be independent of the electrode used and at pH 4 produced a linear range from 20 to 165 microM, and a limit of detection of 7.5 microM for sulfide detection was achieved.

Journal Article↗

PubMed2003

Identification and isolation of multipotential neural progenitor cells from the subcortical white matter of the adult human brain.

The subcortical white matter of the adult human brain harbors a pool of glial progenitor cells. These cells can be isolated by fluorescence-activated cell sorting (FACS) after either transfection with green fluorescent protein (GFP) under the control of the CNP2 promoter, or A2B5-targeted immunotagging. Although these cells give rise largely to oligodendrocytes, in low-density culture we observed that some also generated neurons. We thus asked whether these nominally glial progenitors might include multipotential progenitor cells capable of neurogenesis. We found that adult human white-matter progenitor cells (WMPCs) could be passaged as neurospheres in vitro and that these cells generated functionally competent neurons and glia both in vitro and after xenograft to the fetal rat brain. WMPCs were able to produce neurons after their initial isolation and did not require in vitro expansion or reprogramming to do so. These experiments indicate that an abundant pool of mitotically competent neurogenic progenitor cells resides in the adult human white matter.

Adolescent↗

PubMed2003

A novel mutation in the RDS/Peripherin gene causes adult-onset foveomacular dystrophy.

PURPOSE: To describe a novel mutation in the RDS/Peripherin gene that results in a moderately severe form of adult-onset foveomacular dystrophy. DESIGN: Observational case series. METHODS: Selected members of a family with adult-onset foveomacular dystrophy underwent complete ophthalmic evaluation, including fundus photography and fluorescein angiography, in a tertiary care referral center. The study population consisted of 12 members of a Caucasian kindred. After providing informed consent, patients donated blood for genomic DNA extraction and mutational screening using standard techniques. The main outcome measure were the presence of a RDS/Peripherin gene mutation in a patient with the disease and its absence in unaffected family members and controls. RESULTS: Eight affected family members and no unaffected family members demonstrated a single guanine base deletion at nucleotide 112 that led to premature termination at amino acid 38 of RDS/Peripherin polypeptide. This frameshift mutation results in truncation of nearly 90% of the gene product, thus probably representing a null allele. That results in a relatively severe phenotype, with choroidal neovascularization developing in two patients and geographic atrophy involving the macula in three patients. CONCLUSIONS: We describe a frameshift null mutation in the RDS/Peripherin gene associated with a relatively severe manifestation of adult-onset foveomacular dystrophy in affected family members.

Adult↗