Biomedical subjects

H Qin

Publications and source records attributed to H Qin.

At least 37 records · Page 2Linked to original sources

PubMed2001

Aggregated DsRed-tagged Cx43 and over-expressed Cx43 are targeted to lysosomes in human breast cancer cells.

To investigate if either wild-type or aggregated Cx43 is abnormally targeted to lysosomes in human breast tumor cells, we examined the fate of DsRed-tagged Cx43 and over-expressed Cx43 in communication-deficient HBL-100 and MDA-MB-231 cells. DsRed-tagged Cx43 was assembled into gap junctions in control normal rat kidney cells that express endogenous Cx43 but not in Cx43-negative HBL-100 cells. However, when HBL-100 cells were engineered to coexpress wild-type Cx43 a population of DsRed-tagged Cx43 was rescued and assembled into gap junctions. Co-expression of wild-type Cx26 failed to rescue the assembly of DsRed-tagged Cx43 into gap junctions. Immunolocalization studies revealed that DsRed-tagged Cx43 was aggregated and partially localized to lysosomes. Interestingly, when human MDA-MB-231 breast tumor cells over-expressed wild-type Cx43, Cx43 protein primarily localized to lysosomes. Together, these studies provide evidence for Cx43 being targeted to lysosomes as a result of misfolding and aggregation, while in other cases, the delivery of wild-type Cx43 to lysosomes appears to be due to defects innate to the breast tumor cell type.

Animals↗

PubMed2001

[Resection of gastric carcinoma with preserving of the spleen and pancreas and functional clearance lymph nodes of the spleen hillus and splenic artery].

OBJECTIVE: To study the practical effects of the preserved spleen and pancreas and functional, clearance of lymph nodes of the spleen hillus and splenic artery for gastric carcinoma. METHODS: Spleen and pancreatic involvement was retrospectively reviewed in 439 cases of resectable carcinoma of the gastric cardia, gastric corpus and total stomach. During gastric operation, 2 ml methylene blue was injected into the subserosal space of the gastric cardia or corpus to observe the spreading of lymphatic flow of the stomach in 54 cases. The No10, No11 lymph node metastasis rates, postoperative complications and survival rates were observed in 63 case of gastric carcinoma that had received gastrectomy with preservation of the spleen and pancreas (PSP) and functional clearance of lymph nodes of the spleen hillus and splenic artery. RESULTS: Invasion of gastric cancer into the pancreas and spleen occurred in 5.7% (25/439) and 2.3% (10/439) respectively. Methylence blue was injected into the subserosal space of the stomach without diffusion into the spleen and pancreas. The No10, No11 lymph node metastasis rates of PSP, pancreas preservation (PR) and pancreas and spleen resection (PSR) were 17.5% (11/63), 19.1% (12/63); 20.8% (45/216), 25% (54/216); 20% (6/30), 23% (7/30), respectively (P > 0.05). The occurrence of postoperative complications and mortality was lower in patients with PSP than those with spleen and parts of pancreas resected, whereas the survival rate was higher in patients with PSP. The 5-year and 10-year survival rates of gastric carcinoma in stage II, III a were markedly improved in patients with PSP. CONCLUSIONS: PSP for patients with gastric cancer is safe and functional resectable. The occurrence of postoperative complications is lower and the survival rates are higher in patients with PSP than those with spleen and part of pancreas resected. PSP is beneficial to those with gastric carcinoma in stage II, IIIa.

Adult↗

PubMed2000

DNA sequence of both chromosomes of the cholera pathogen Vibrio cholerae.

Here we determine the complete genomic sequence of the gram negative, gamma-Proteobacterium Vibrio cholerae El Tor N16961 to be 4,033,460 base pairs (bp). The genome consists of two circular chromosomes of 2,961,146 bp and 1,072,314 bp that together encode 3,885 open reading frames. The vast majority of recognizable genes for essential cell functions (such as DNA replication, transcription, translation and cell-wall biosynthesis) and pathogenicity (for example, toxins, surface antigens and adhesins) are located on the large chromosome. In contrast, the small chromosome contains a larger fraction (59%) of hypothetical genes compared with the large chromosome (42%), and also contains many more genes that appear to have origins other than the gamma-Proteobacteria. The small chromosome also carries a gene capture system (the integron island) and host 'addiction' genes that are typically found on plasmids; thus, the small chromosome may have originally been a megaplasmid that was captured by an ancestral Vibrio species. The V. cholerae genomic sequence provides a starting point for understanding how a free-living, environmental organism emerged to become a significant human bacterial pathogen.

Base Sequence↗

PubMed2000

Complete genome sequence of Neisseria meningitidis serogroup B strain MC58.

The 2,272,351-base pair genome of Neisseria meningitidis strain MC58 (serogroup B), a causative agent of meningitis and septicemia, contains 2158 predicted coding regions, 1158 (53.7%) of which were assigned a biological role. Three major islands of horizontal DNA transfer were identified; two of these contain genes encoding proteins involved in pathogenicity, and the third island contains coding sequences only for hypothetical proteins. Insights into the commensal and virulence behavior of N. meningitidis can be gleaned from the genome, in which sequences for structural proteins of the pilus are clustered and several coding regions unique to serogroup B capsular polysaccharide synthesis can be identified. Finally, N. meningitidis contains more genes that undergo phase variation than any pathogen studied to date, a mechanism that controls their expression and contributes to the evasion of the host immune system.

Antigenic Variation↗

PubMed2000

Effects of extracellular matrix on phenotype modulation and MAPK transduction of rat aortic smooth muscle cells in vitro.

The transition of arterial smooth muscle cells (SMCs) from a contractile to a synthetic phenotype may play an essential role in the formation of atherosclerotic and restenotic lesions. This process includes a prominent structural reorganization and allows cells to acquire the ability to migrate, proliferate, and secrete extracellular matrix components. According to Western blotting analysis and immunohistochemical and morphological observations, laminin not only retains SMCs in a contractile state but also possibly stimulates cells to transform a synthetic to a contractile phenotype at an early stage, mediated by P38 MAPK signal transduction. However, fibronectin promotes SMCs to transform from a contractile to a synthetic phenotype, mediated by the ERK MAPK signal pathway. The localization of smooth muscle alpha -actin, myosin heavy chain isoform SM2, and vimentin in explant-isolated rat SMCs was affected by a substrate of fibronectin and laminin and also by ERK MAP kinase inhibitor (PD098059) and P38 MAPK inhibitor (SB203580). Furthermore, vimentin may play a much more important role in differentiation than desmin in phenotype modulation in rat aortic smooth muscle cells.

Actins↗

PubMed2000

Frequency of cytochrome P450 3A4 variant genotype in transplant population and lack of association with cyclosporin clearance.

OBJECTIVE: Cytochrome P450 3A4 (CYP3A4) plays a vital role in the oxidative metabolism of many xenobiotics. Some recent reports have provided circumstantial evidence in support of an association between a genetic polymorphism (A-->G) in the 5'-flanking region (-290) of CYP3A4 and altered enzyme activity. We sought to determine whether genotyping patients for CYP3A4-G could assist with the dose optimisation of drugs metabolised by this system. METHODS: Normal subjects and renal-transplant patients receiving cyclosporin for immune modulation were genotyped for the CYP3A4-G variant. A surrogate for cyclosporin clearance was estimated from the ratio of the cyclosporin dose, normalised for body weight and the corresponding trough concentration. The association between genotype and clearance was examined in patients who received twice-daily doses of cyclosporin and who were not on concurrent medication known to modify CYP3A4 function. RESULTS: The allelic frequencies of the CYP3A4-G variant were estimated to be 2.6% and 3% in transplant patients and normal subjects, respectively. The median cyclosporin pseudo-clearance of transplant patients with wild-type CYP3A4 was 0.90 l/h/kg (range: 0.35-3.8 l/h/kg; n = 86), whereas the corresponding value for the five patients heterozygotic for the CYP3A4-G variant was 0.71 l/h/kg (range 0.35-0.91 l/h/kg). The distribution of the pseudo-clearance according to genotype was not found to be significant according to a Fisher's exact test (P = 0.15). CONCLUSION: Genotyping for the CYP3A4-G polymorphism is unlikely to assist cyclosporin dose selection in transplant patients.

Adolescent↗

PubMed2000

[Significance and expression of insulin-like growth factor II and its receptor in hepatocellular carcinogenesis].

OBJECTIVE: To provide information on the potential role of insulin-like growth factor II (IGF-II) and insulin-like growth factor II receptor (IGF-IIR) during different liver diseases and hepatocarcinogenesis. METHODS: Southern hybridization was used to detect HBV DNA integration in various kinds of liver tissues, and DNA-RNA in situ hybridization to observe and analyze the mRNA of IGF-II and IGF-II receptor in chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC). RESULTS: The expression of IGF-II and IGF-II receptor mRNA was observed not only in HCC, but also in chronic hepatitis and cirrhosis. An increasing gradient of IGF-II and IGF-IIR Mrna expression was in turn from chronic hepatitis (33. 3%), HCC (66.7%) to cirrhosis (72.0%). Strongly positive expression was found in liver cell dysplasia, regenerative nodules and poorly differentiated HCC cells. CONCLUSION: IGF-II and its receptor might play an important role in the development of HCC.

Adult↗

PubMed2000

Synergetic effect of dialyzer membrane and lipopolysaccharide on peripheral blood mononuclear cell cytokine production in uremic patients.

OBJECTIVE: To investigate the effect of lipopolysaccharide(LPS) and dialyzer membrane on cytokine gene expression and protein production in uremic patients on continuous ambulatory peritoneal dialysis (CAPD) and regular hemodialysis(HD). METHODS: Interleukin-1 beta (IL-1 beta) and interleukin-1 receptor antagonist (IL-1Ra) produced by cultured peripheral blood mononuclear cells (PBMC) after exposure to cuprammonium (Cup) membrane, polysulfone (PS) membranes or endotoxin were detected using enzyme-linked immunoabsorbent assay. mRNA expression was determined simultaneously by in situ hybridization. RESULTS: In the absence of endotoxin, a small amount of IL-1 beta and IL-1 Ra was produced by PBMC harvested from HD and CAPD patients after incubation with Cup or PS during subsequent 24-hour culture. For healthy controls, IL-1 beta was barely detectable just above the detection limit. Although no differences could be found in protein synthesis between Cup and PS, in situ hybridization showed that Cup induced markedly higher level mRNA coding for IL-1 beta and IL-1Ra. In contrast, when subsequently stimulated with endotoxin, PBMC incubated with Cup could produce significantly larger amount of IL-1 beta and IL-1Ra compared with either unstimulated cells or post-incubation PBMC with PS. LPS-stimulated PBMC in healthy subjects produced similar amount of IL-1 beta and markedly lower IL-1Ra as compared with uremic patients on HD and CAPD. CONCLUSIONS: Two steps are required in healthy control for IL-1 beta and IL-1Ra production: induction of mRNA transcription by membrane contact, followed by LPS-induced translation, while in uremic patients on HD or CAPD bioincompatibility-membrane and LPS have a synergetic effect on IL-1 beta and IL-1Ra production. There exists an unbalance between IL-1 beta and its specific inhibitor in maintenance dialysis patients.

Adult↗

PubMed2000

Gastric rupture caused by acute gastric distention in non-neonatal children: clinical analysis of 3 cases.

OBJECTIVE: To study gastric rupture, a progressive, rapid and high mortality condition, caused by acute gastric distention (GRAGD) and its appropriate diagnosis and treatment. METHODS: The etiology, pathology, clinical manifestations and experiences in 3 children with GRAGD were reviewed. RESULTS: Case 1: After diagnosing GRAGD and stabilizing her shock with massive fluid replacement, gastrostomy was performed. Her postoperative course was uneventful because of fasting, suction, fluid infusion, correction of acidosis and supporting nutrition. Case 2: After diagnosing gastric distention which subsided with conservative therapy for 9 days, she suddenly had gastric rupture when she had not eaten for 6 days. She died of shock and had no chance for surgery. Case 3: The patient had sudden abdominal pain, distention and vomiting with severe shock for 4 days. Emergency surgery found gastric rupture and the method was the same as Case 1. The patient survived but has brain impairment. Case 1 and 3 showed multifocal transmural necrosis. CONCLUSIONS: Symptoms like overeating, bulimia, changes in kind of food, X-ray showing large distended stomach and massive pneumoperitoneum were seen after gastric rupture and can help to diagnose this condition. Clinical course of gastric distention with toxic shock progresses rapidly, however subsequent gastric rupture exacerbates the shock and makes the treatment difficult treatment. It is extremely important that a laparotomy be performed at once after stabilizing shock with massive fluid replacement. Postoperative nutritional support and fluid replacement will increase survival. It is very important that when gastric distention disappears after conservative therapy, the doctor should assess carefully whether the gastric wall recovery is under way by using effective methods of examination.

Abdominal Pain↗

PubMed2000

[Down regulation of HER2/neu expression by adenovirus E1A and its anti-tumor activity].

OBJECTIVE: To study the growth inhibitory and chemo-sensitizing effects of adenovirus E1A gene on HER2/neu-overexpressing tumor cell lines. METHODS: E1A was transfected in vitro and in vivo by adenovirus vector into HER2/neu overexpressing human mammary cancer cell lines MDA-MB-453 and SKBR3 and their growth was monitored. The chemo-sensitizing effect was examined by MTT assay. RESULTS: E1A greatly inhibited growth of HER2/neu-overexpressing tumor and prolonged the survival time of tumor-bearing mice. Western blot and immunohistochemical analysis both showed suppression of p185 protein expression in E1A-transfected HER2/neu overexpressing cancer cell lines. E1A could sensitize HER2/neu-overexpressing human breast cancer cells to Taxotere by repressing HER2/neu expression. CONCLUSION: Adenovirus E1A inhibits tumor growth and sensitizes tumor cells to chemotherapeutic agent via down regulation of HER2/neu expression.

Adenoviridae↗

PubMed2000

[Terminal differentiation of human acute promyelocytic leukemia (APL) cells induced by Tanshinone II A in primary culture].

The aim of this study was to investigate whether Tanshinone II A (Tan II A) can induce human acute promyelocytic leukemia (APL) cells to differentiate or not in primary culture. The APL cells from 5 cases were cultured respectively with Tan II A at the concentration of 0.5 microgram/ml for 7 days in vitro. The differentiations of these leukemia cells were observed cytomorphologically and examined by nitroblue tetrazolium (NBT) test. The cell DNA cycle and membrane cluster differentiation (CD) antigens (CD33, CD11b) were analyzed by flow cytometry. The results showed that 82.5% +/- 4.8% of APL cells were induced into morphologically and functionally differentiated cells. The cell growth curve showed that the growth of APL cells was inhibited. The degree of differentiation and growth inhibition induced by Tan II A was not different from that by ATRA (P > 0.05). Flow cytometry analysis showed that Tan II A arrested APL cells in G0/G1 phase and inhibited cellular DNA synthesis. This study demonstrates that Tan II A can induce differentiation of APL cells in vitro, and hence it is worthy of further studies for clinical use.

Abietanes↗

PubMed1999

Genome sequence of the radioresistant bacterium Deinococcus radiodurans R1.

The complete genome sequence of the radiation-resistant bacterium Deinococcus radiodurans R1 is composed of two chromosomes (2,648,638 and 412,348 base pairs), a megaplasmid (177,466 base pairs), and a small plasmid (45,704 base pairs), yielding a total genome of 3,284, 156 base pairs. Multiple components distributed on the chromosomes and megaplasmid that contribute to the ability of D. radiodurans to survive under conditions of starvation, oxidative stress, and high amounts of DNA damage were identified. Deinococcus radiodurans represents an organism in which all systems for DNA repair, DNA damage export, desiccation and starvation recovery, and genetic redundancy are present in one cell.

Bacterial Proteins↗

PubMed1999

The transcription factors Sp1, Sp3, and AP-2 are required for constitutive matrix metalloproteinase-2 gene expression in astroglioma cells.

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that contribute to pathological conditions associated with angiogenesis and tumor invasion. MMP-2 is highly expressed in human astroglioma cells, and contributes to the invasiveness of these cells. The human MMP-2 promoter contains potential cis-acting regulatory elements including cAMP response element-binding protein, AP-1, AP-2, PEA3, C/EBP, and Sp1. Deletion and site-directed mutagenesis analysis of the MMP-2 promoter demonstrates that the Sp1 site at -91 to -84 base pairs and the AP-2 site at -61 to -53 base pairs are critical for constitutive activity of this gene in invasive astroglioma cell lines. Electrophoretic gel shift analysis demonstrates binding of specific DNA-protein complexes to the Sp1 and AP-2 sites: Sp1 and Sp3 bind to the Sp1 site, while the AP-2 transcription factor binds the AP-2 element. Co-transfection expression experiments in Drosophilia SL2 cells lacking endogenous Sp factors demonstrate that Sp1 and Sp3 function as activators of the MMP-2 promoter and synergize for enhanced MMP-2 activation. Overexpression of AP-2 in AP-2-deficient HepG2 cells enhances MMP-2 promoter activation. These findings document the functional importance of Sp1, Sp3, and AP-2 in regulating constitutive expression of MMP-2. Delineation of MMP-2 regulation may have implications for development of new therapeutic strategies to arrest glioma invasion.

Animals↗

PubMed1999

Substitution of the sixth axial ligand of Rhodobacter capsulatus cytochrome c1 heme yields novel cytochrome c1 variants with unusual properties.

The cytochrome (cyt) c1 heme of the ubihydroquinone:cytochrome c oxidoreductase (bc1 complex) is covalently attached to two cysteine residues of the cyt c1 polypeptide chain via two thioether bonds, and the fifth and sixth axial ligands of its iron atom are histidine (H) and methionine (M), respectively. The latter residue is M183 in Rhodobacter capsulatus cyt c1, and previous mutagenesis studies revealed its critical role for the physicochemical properties of cyt c1 [Gray, K. A., Davidson, E., and Daldal, F. (1992) Biochemistry 31, 11864-11873]. In the homologous chloroplast b6f complex, the sixth axial ligand is provided by the amino group of the amino terminal tyrosine residue. To further pursue our investigation on the role played by the sixth axial ligand in heme-protein interactions, novel cyt c1 variants with histidine-lysine (K) and histidine-histidine axial coordination were sought. Using a R. capsulatus genetic system, the cyt c1 mutants M183K and M183H were constructed by site-directed mutagenesis, and chromatophore membranes as well as purified bc1 complexes obtained from these mutants were characterized in detail. The studies revealed that these mutants incorporated the heme group into the mature cyt c1 polypeptides, but yielded nonfunctional bc1 complexes with unusual spectroscopic and thermodynamic properties, including shifted optical absorption maxima (lambdamax) and decreased redox midpoint potential values (Em7). The availability and future detailed studies of these stable cyt c1 mutants should contribute to our understanding of how different factors influence the physicochemical and folding properties of membrane-bound c-type cytochromes in general.

Amino Acid Substitution↗

PubMed1999

Structural basis of procaspase-9 recruitment by the apoptotic protease-activating factor 1.

Caspase-9-mediated apoptosis (programmed cell death) plays a central role in the development and homeostasis of all multicellular organisms. Mature caspase-9 is derived from its procaspase precursor as a result of recruitment by the activating factor Apaf-1. The crystal structures of the caspase-recruitment domain of Apaf-1 by itself and in complex with the prodomain of procaspase-9 have been determined at 1.6 and 2.5 A resolution, respectively. These structures and other evidence reveal that each molecule of Apaf-1 interacts with a molecule of procaspase-9 through two highly charged and complementary surfaces formed by non-conserved residues; these surfaces determine recognition specificity through networks of intermolecular hydrogen bonds and van der Waals interactions. Mutation of the important interface residues in procaspase-9 or Apaf-1 prevents or reduces activation of procaspase-9 in a cell-free system. Wild-type, but not mutant, prodomains of caspase-9 completely inhibit catalytic processing of procaspase-9. Furthermore, analysis of homologues from Caenorhabditis elegans indicates that recruitment of CED-3 by CED-4 is probably mediated by the same set of conserved structural motifs, with a corresponding change in the specificity-determining residues.

Amino Acid Sequence↗

PubMed1999

Q-Band resonance Raman investigation of turnip cytochrome f and Rhodobacter capsulatus cytochrome c1.

The results of a comprehensive Q-band resonance Raman investigation of cytochrome c1 and cytochrome f subunits of bc1 and b6f complexes are presented. Q-band excitation provides a particularly effective probe of the local heme environments of these species. The effects of protein conformation (particularly axial ligation) on heme structure and function were further investigated by comparison of spectra obtained from native subunits to those of a site directed c1 mutant (M183L) and various pH-dependent species of horse heart cytochrome c. In general, all species examined displayed variability in their axial amino acid ligation that suggests a good deal of flexibility in their hemepocket conformations. Surprisingly, the large scale protein rearrangements that accompany axial ligand replacement have little or no effect on macrocycle geometry in these species. This indicates the identity and/or conformation of the peptide linkage between the two cysteines that are covalently linked to the heme periphery may determine heme geometry.

Brassica↗

PubMed1999

Alpha-galactose based neoglycopeptides. Inhibition of verotoxin binding to globotriosylceramide.

Solution and solid phase strategies for the synthesis of alpha-galactose based neoglycopeptide derivatives 2-13 were developed. Neoglycopeptides generated were tested for the inhibition of verotoxin binding to globotriosylceramide (Gb3) using ELISA. Among all of the compounds tested, only the lipid derivatives of neoglycopeptides, 11, 12 and 13 were found to be inhibitors, IC50 = 2.0 mM (11b and 12c) and 0.2 mM (11c and 13c). All of the inhibitors (11b, 11c, 12c and 13c) have a similar branching of the two alpha-galactosyl units at the N-terminal glycine residue of a short peptide and a lipid moiety attached at the C-terminal site. Both of these factors seem to be crucial for the inhibition. It is interesting to note that the inhibitors have only a portion of the natural trisaccharide ligand. The secondary groups either may contribute in sub-site oriented interactions with the protein receptors or may mimic the internal sugar units of the cell-surface ligand, Gb3.

Anti-Infective Agents↗

PubMed1999

Construction and characterization of a chimeric fusion protein consisting of an anti-idiotype antibody mimicking a breast cancer-associated antigen and the cytokine GM-CSF.

Anti-idiotype antibody, 11D10 mimics biologically and antigenically a distinct and specific epitope of the high molecular weight human milk fat globule (HMFG), a cancer-associated antigen present in over 90% of breast tumor samples. To augment the immunogenicity of 11D10 without the aid of a carrier protein or adjuvant, we made a chimeric 11D10-GM-CSF fusion protein for use as a vaccine. An expression plasmid for 11D10 was made by ligation of the DNA sequences of the 11D10 light-chain variable region upstream of the human kappa constant region. The heavy-chain plasmid carrying GM-CSF was made by ligation of the heavy-chain variable region sequences upstream of the human gamma1 constant region CH1 fused to the DNA fragment encoding the mature GM-CSF peptide 3' to the CH3 exon. NS1 plasmacytoma cells were transfected with the light and heavy-chain vectors by electroporation. Fusion protein secreted in the culture medium was purified and was characterized by gel electrophoresis as well as by determination of the biological activity of the fused GM-CSF. In nonreducing SDS-polyacrylamide gels, a single band approximately 200 Kd reacted with anti-human kappa, anti-human lambda1 and anti-GM-CSF antibodies. In reducing polyacrylamide gels, a approximately 74 kd protein reacted with anti-human lambda1 and anti-GM-CSF antibodies. The fusion protein induced proliferation of GM-CSF dependent NFS-60 cells. These results suggest that the protein is a chimeric anti-idiotype antibody consisting of 11D10 variable domains, human kappa and lambda1 constant domains and that the GM-CSF moiety fused to the constant region lambda1 is biologically active.

Adjuvants, Immunologic↗