Biomedical subjects

H Qin

Publications and source records attributed to H Qin.

At least 73 records · Page 4Linked to original sources

PubMed1997

Basic FGF regulates interstitial collagenase gene expression in human smooth muscle cells.

Basic fibroblast growth factor (bFGF) is a mitogenic factor that is implicated in smooth muscle cell growth in atherosclerosis and vascular restenosis. In this study, we examined the effect of bFGF on the expression of the interstitial collagenase gene in human vascular smooth muscle cells. Results from Northern transfer analysis showed that bFGF increased collagenase mRNA levels greater than threefold as early as 24 h. Collagenase pre-mRNA levels were elevated approximately threefold by bFGF, according to RT-PCR analysis. Transient transfections of the smooth muscle cells with a 4.4-kb human collagenase promoter-CAT reporter gene, however, failed to show upregulation of the promoter activity by bFGF. Interestingly, transfections with deleted fragments containing promoter sequences from -1047 to -2271 resulted in modest stimulation of the collagenase-CAT promoter activity by bFGF, bFGF did not alter the stability of the collagenase mRNA, as demonstrated by degradation studies. The enhanced collagenase mRNA levels elicited by bFGF were reflected in increased amounts of collagenase protein that were detected by Western blot analysis. In summary, bFGF upregulates the interstitial collagenase expression, resulting in turnover of the extracellular matrix, an event that could facilitate smooth muscle cell migration and proliferation during the early stages of atherosclerosis and restenosis.

Cells, Cultured↗

PubMed1996

Isolation and characterization of vibrational spectra of individual heme active sites in cytochrome bc1 complexes from Rhodobacter capsulatus.

Resonance Raman spectra of bc1 complexes and isolated c1 subunit from Rhodobacter capsulatus have been obtained using a variety of excitation wavelengths. Spectra obtained via Q-band excitation of bc1 complexes in different redox states were separated to yield the individual vibrational spectra of each of the three heme active sites. Hemes bH and c1 exhibit vibrational spectra typical of b- and c-type hemes, respectively. In contrast, the spectrum of heme bL is anomalous with respect to those of other hemes b. The isolated spectra were also used to assess the effects of inhibitor binding on the local structural environments of the hemes. Neither antimycin nor myxothiazol binding produces dramatic structural perturbations at the hemes. Heme c1 is completely unaffected by the presence of either inhibitor. The vibrational spectra of hemes bH and bL are slightly altered by antimycin and myxothiazol binding, respectively.

Antimycin A↗

PubMed1996

Cancer gene therapy using tumor cells infected with recombinant vaccinia virus expressing GM-CSF.

The efficacy of a recombinant vaccinia virus (rvv-mGM-CSF) expressing murine granulocyte-macrophage colony stimulating factor (GM-CSF) for use in cancer gene therapy was evaluated. C57BL/6 mice with established B16-F10 melanoma were treated by s.c. injection of irradiated B16 cells infected with two different recombinant vaccinia virus (rvv) constructs. Mice treated with rvv-mGM-CSF vaccine survived longer (p < 0.05), were free of palpable tumors (> 4 mm) longer (p < 0.02), and had smaller mean tumor volumes (p < 0.005) compared to those treated with irradiated B16 cells infected with a control rvv (rvv-lacZ) expressing Escherichia coli beta-galactosidase or irradiated uninfected B16 cells. The vaccine appeared to be B16 tumor cell specific, because there was no therapeutic effect when heterologous but syngeneic (H-2b) colon adenocarcinoma cells, MC-38 infected with rvv-mGM-CSF were used as vaccine. In this model, rvv expressing interleukin-2 (IL-2) was ineffective. In addition, experimental lung metastasis of B16 tumor cells was significantly inhibited by rvv-mGM-CSF vaccine compared to several control vaccines when the vaccine was applied either by i.p. route (p < 0.006) or by s.c. injection (p < 0.0008). B16 cells expressing mGM-CSF after infection with rvv-mGM-CSF or transduction with a retroviral vector, were equally effective (p > 0.14) as vaccines against lung metastasis. Inhibition of metastasis was also B16 tumor cell specific. These data suggest that this approach of cancer gene therapy has a potential for use in cancer patients.

Adenocarcinoma↗

PubMed1996

Axial heme ligation in the cytochrome bc1 complexes of mitochondrial and photosynthetic membranes. A near-infrared magnetic circular dichroism and electron paramagnetic resonance study.

The combination of EPR and low-temperature near-IR magnetic circular dichroism spectroscopies have been used to investigate the axial ligation of the cytochromes in the cytochrome bc1 complexes from bovine heart mitochondria, Rhodobacter capsulatus, Rhodobacter sphaeroides, and Rhodospirillum rubrum, and the purified cytochromes c1 from bovine heart mitochondria, Rb. capsulatus and Rb. sphaeroides. The possibility of axial ligation of cytochrome c1 by the amino terminus of the polypeptide was also assessed by acetylating the N-terminus of Rb. capsulatus cytochrome c1 and comparing the properties of the acetylated and unmodified samples. The results are consistent with bis-histidine axial ligation for the high- and low-potential b-type cytochromes and histidine/methionine axial ligation for the c1-type cytochrome in the intact cytochrome bc1 complexes. Purified samples of cytochrome c1 are mixtures of two forms, one with histidine/methionine and the other with bis-histidine axial ligation. The form with bis-histidine axial ligation is also assembled in the M183L mutant of the Rb. capsulatus cyt bc1 complex in which the methionine residue coordinating cyt c1 is replaced by a leucine. The bis-histidine form appears to be an artifact of dissociation of cytochrome c1 from the cytochrome bc1 complex and is greatly enhanced particularly in the bacterial cytochromes c1 by sample handling and the addition of 50% (v/v) ethylene glycol or glycerol.

Amino Acid Sequence↗

PubMed1996

Identification of a gag-encoded cytotoxic T-lymphocyte epitope from FBL-3 leukemia shared by Friend, Moloney, and Rauscher murine leukemia virus-induced tumors.

FBL-3 is a highly immunogenic murine leukemia of C57BL/6 origin induced by Friend murine leukemia virus (MuLV). Immunization of C57BL/6 mice with FBL-3 readily elicits CD8+ cytotoxic T lymphocytes (CTL) capable of lysing FBL-3 as well as syngeneic leukemias induced by Moloney and Rauscher MuLV. The aim of this current study was to identify the immunogenic epitope(s) recognized by the FBL-3-specific CD8+ CTL. A series of FBL-3-specific CD8+ CTL clones were generated from C57BL/6 mice immunized to FBL-3. The majority of CTL clones (32 of 38) were specific for F-MuLV gag-encoded antigen. By using a series of recombinant vaccinia viruses expressing full-length and truncated F-MuLV gag genes, the antigenic epitope recognized by the FBL-3 gag-specific CTL clones, as well as by bulk-cultured CTL from spleens of mice immune to FBL-3, was localized to the leader sequence of gPr80gag protein. The precise amino acid sequence of the CTL epitope in the leader sequence was identified as CCLCLTVFL (positions 85-93) by examining lysis of targets incubated with a series of synthetic leader sequence peptides. No evidence of other CTL epitopes in the gPr80gag or Pr65gag core virion structural polyproteins was found. The identity of CCLCLTVFL as the target peptide was validated by showing that immunization with the peptide elicited CTL that lysed FBL-3. The CTL elicited by the Gag peptide also specifically lysed syngeneic leukemia cells induced by Moloney and Rauscher MuLV (MBL-2 and RBL-5). The transmembrane peptide was shown to be the major gag-encoded antigenic epitope recognized by bulk-cultured CTL derived from C57BL/6 mice immunized to MBL-2 or RBL-5. Thus, the CTL epitope of FBL-3 is localized to the transmembrane anchor domain of the nonstructural Gag polyprotein and is shared by leukemia/lymphoma cell lines induced by Friend, Moloney, and Rauscher MuLV.

Animals↗

PubMed1996

[CD4+ T-cell immunity and Ab responses to mutant ras protein in pancreas and colon cancer patients].

Mutated p21 ras protein contains single substituted amino acid residue. It can be considered as cancer-specific protein. The current study examined whether T-cell and Ab responses to mutant p21 ras protein and/or peptide can be detected in patients with pancreatic or colon cancer. Studies focused on the aspartic acid substitution in amino acid position 12(ras D12) as the commonest mutation in gastrointestinal malignancy. IgA antibodies directed against mutated ras D12 protein were detected in 51 of 160 (31.8%) colon cancer patients, but only in 1 of 40 (2.5%) normals. The greater incidence of antibody in cancer patients provides evidence that immunization to the ras proteins occurred as a result of the malignancy. Seven of sixteen (43.7%) pancreas cancer patients responded to ras D12 peptide. T cell responses to ras D12 peptides were detected in only 2 of 25 (8.0%) colon cancer patients. None of the 11 normal individuals tested had positive responses to normal or mutant ras p21 proteins and/or peptides. Thus, Ab and CD4+ T cell immunity to the mutated segment of ras protein is present in some patients with gastrointestinal cancer.

CD4-Positive T-Lymphocytes↗

PubMed1996

[Electroacupuncture along meridians activating subcutaneous primary afferents in acupoints--CB-HRP tracing study].

The experiment was performed to observe the segmental distribution of sensory afferent nerves in acupoints and the influence of electroacupuncture (EA) along meridians on it. 1% CB-HRP solution (5 microliters) was injected subcutaneously at unilateral "Zusanli" or "Ruzhong" acupoint of rats. The HRP labeled cells were counted in the related spinal dorsal root ganglia (DRG). The results were as follows: the sensory nerve terminals of "Zusanli" acupoint mainly projected to the neurons of L4 and L5 DRG and that of "Ruzhong" acupoint projected to the neurons of T4, T5 and T6 DRG; sensory nerve terminals of "Zusanli" or "Ruzhong" acupoint were activated by the EA stimulation along meridians, their ability of uptaking HRP was enhanced, so the HRP labeled cells increased in the related DRG, the HRP labeled DRG segments spread. This study provides a new morphological evidence for the mechanism's explanation of propagated sensation along the meridians.

Acupuncture Points↗

PubMed1996

[A study on lens epithelial cell DNA damage induced by hydrogen peroxide in rat and its repair].

OBJECTIVE: The induction and repair of DNA single-strand breaks (SSBs) were measured in primary cultured infant rat lens epithelial cells (RLECs) following hydrogen peroxide (HP) exposure, and the influential factors were detected. METHODS: Utilizing nick translation methodology which utilizes incorporation of labeled nucleotides at the sites of DNA SSBs to sensitively quantitate the damage, we studied the effects of temperature, doses of HP and trace amount of selenium on cell survival. RESULTS: The number of DNA SSBs at 37 degrees was higher than that at 4C (P < 0.01). Significant numbers of SSBs were detected after being insulted by as low as 36.4 mumol/L hydrogen peroxide for 12 minutes 4 degrees (P < 0.05). Repair rapidly initiated and almost completed in 60 minutes after mild damage, and it was unable to repair when the DNA damage was induced by HP at toxic concentration. Trace selenium was added to the culture and incubated for 24 hours, then the number of SSBs was significantly decreased (P < 0.01). CONCLUSIONS: At 37 degrees HP may induce DNA SSBs in RLECs. HP induces the SSBs in a dose dependent manner. The DNA SSBs can not be repaired after severe damage. Trace selenium can decrease the degree of susceptibility to oxidative damage in infant RLECs.

Animals↗

PubMed1995

Platelet-derived growth factors-AA and -BB regulate collagen and collagenase gene expression differentially in human fibroblasts.

Platelet-derived growth factor (PDGF) is a mitogen associated with tissue repair, a process involving collagen synthesis and remodelling by interstitial collagenase. This study examines and compares the regulation of interstitial collagenase and collagen gene expression by PDGF-AA and -BB in human fibroblasts. Time-course analysis showed that neither PDGF-AA or -BB had a consistent effect on the expression of pro-alpha 1(I) or pro-alpha 2(I) type-I collagen genes. In contrast, interstitial collagenase gene expression was found to be consistently up-regulated severalfold by PDGF-BB. Enhanced expression of the collagenase gene was not apparently due to up-regulation of its promoter activity in human dermal fibroblasts, as indicated by transient and stable transfection experiments. Unlike PDGF-BB, PDGF-AA did not alter collagenase mRNA levels under low-serum culture conditions. Thus, the biological activities of the PDGF homodimers are different, with PDGF-BB being clearly more potent than PDGF-AA in its regulation of collagenase gene expression.

Becaplermin↗

PubMed1995

CD4+ T-cell immunity to mutated ras protein in pancreatic and colon cancer patients.

Mutated p21 ras proteins contain single substituted amino acid residues and represent cancer-specific proteins. The current study examined whether primed T cell immunity to mutant p21 ras proteins and/or peptides can be detected in patients with pancreatic or colon cancer. Studies focused on the aspartic acid substitution in amino acid position 12 (denoted D12) as the commonest mutation in gastrointestinal malignancy. Peripheral blood lymphocytes from patients or normal individuals were tested for the ability to proliferate in response to normal or mutated ras peptides or proteins. T-cell responses were defined as a stimulation index of > 2.0. Results showed that 7 of 16 (44%) pancreatic cancer patients responded to ras-D12 peptide. Responses to ras-D12 protein were studied in only the last four patients that responded to D12 peptides. Three of the 4 patients that responded to ras-D12 peptide showed a substantial response to p21 ras-D12 protein (stimulation indices of 12, 8, and 24). Specificity was validated by examining responses to normal and alternate ras peptides and proteins. T-cell responses to ras-D12 peptides were detected in only 2 of 25 (8%) colon cancer patients. None of 11 normal individuals tested had positive responses to normal or mutant ras p21 proteins and/or peptides. Thus, CD4+ T-cell immunity to the mutated segment of ras protein is present in some patients with gastrointestinal cancer.

Amino Acid Sequence↗

PubMed1995

Specific binding of avidin to biotin containing lipid lamella surfaces studied with monolayers and liposomes.

The interaction of avidin (from egg white) with phospholipid (monolayer and bilayer) model membranes containing biotin-conjugated phospholipids has been studied. In the first part, using surface sensitive techniques (ellipsometry and surface plasmon resonance) we demonstrated that the nonspecific adsorption of avidin to phospholipid lamella could be abolished by adding an amount of Ca2+, Mg2+ or Ba2+ that led to an electrostatic interaction. The specific binding of avidin to lipid mixtures containing biotin-conjugated phospholipids was obviously composition dependent. The ratio 1:12 of a B-DPPE/DPPE mixture was found to be the optimum molar ratio. When we compared the results from the surface sensitive techniques with those from the electron micrographs of a two dimensional crystal of avidin (obtained in our laboratory), the optimum ratio was found to be determined by the effect of lateral steric hindrance. In the second part, we observed the pattern of the layers of fluorescently labeled phospholipid and adsorbed proteins with a home-made micro fluorescence film balance. The fluorescence images showed that avidin was preferentially bound to the receptors that were in the fluid domains. Further, with a sensitive fluorescence assay method, the effect of the phase behavior of liposomes on the specific binding of avidin was measured. This showed that avidin interacted with biotinlipid more weakly in the gel state liposome than in the liquid state liposome. The major conclusion was that the binding of avidin to a membrane bound model receptor was significantly restricted by two factors: one was the lateral steric hindrance and the other was the fluidity of the model membrane.

Adsorption↗

PubMed1995

Regulation of N-acetylglucosaminyltransferase V by protein kinases.

When 7721 human hepatocarcinoma cells were treated with 100 nM phorbol-12-myristate-13-acetate (PMA), the activity of N-acetylglucosaminyltransferase V(GnT-V) in the cells varied in accordance with the activity of membranous protein kinase C (PKC), but not with that of cytosolic PKC. Quercetin, a non-specific inhibitor of Ser/Thr protein kinase, and D-sphingosine and staurosporine, two specific inhibitors of PKC, blocked the activation of membranous PKC and GnT-V by PMA. Among the three inhibitors, quercetin was least effective. The inhibitory rates of quercetin and staurosporine toward membranous PKC and GnTV were proportional to the concentrations of the two inhibitors. The activities of GnTV and membranous protein kinase A (PKA) were also induced in parallel by dibutyryl cAMP (db-cAMP) and this induction was blocked by a specific PKA inhibitor. When cell free preparations of 7721 cells and human kidney were treated with alkaline phosphatase (ALP) to remove the phosphate groups, the GnTV activities were decreased. These results suggest that GnTV may be activated by membranous PKC or PKA, indirectly or directly, via phosphorylation of Ser/Thr residues.

Amino Acid Sequence↗

PubMed1995

Two-dimensional crystallization of avidin on biotinylated lipid monolayers.

Two-dimensional crystals of avidin were obtained on mixed lipid monolayers containing biotinylated lipids (N-biotinyl-dipalmitoyl-L-alpha-phosphatidyl ethanolamine and dioleoyl phosphatidyl choline) by specific interaction. Image analysis of electron micrographs of these crystals revealed p2 symmetry with the unit cell parameters a = 66 +/- 2 A, b = 68 +/- 1 A, and gamma = 121 +/- 4 degrees. The projection map showed, at a resolution of about 27 A, that the four subunits within one avidin molecule are separated into two parts. Comparison between avidin and streptavidin reveals that avidin molecule binds to the lipid monolayer in an orientation similar to that of streptavidin.

Avidin↗

PubMed1995

Basic fibroblast growth factor regulates type I collagen and collagenase gene expression in human smooth muscle cells.

Basic fibroblast growth factor (bFGF) is a multifunctional peptide well known for angiogenic, neurotropic, and mesoderm-inducing effects. In the present study, we have investigated the effects of bFGF on collagen and collagenase gene expression in human iliac arterial smooth muscle cells. We report that bFGF inhibits type I collagen gene expression and collagen biosynthesis, with concomitant stimulation of collagenase gene expression. The smooth muscle cells incubated with human recombinant bFGF decreased the mRNA steady state levels of pro-alpha 1(I) type I collagen by as much as 72%. [3H]Hydroxyproline synthesis was also suppressed by 59% compared with untreated control cultures. Indirect immunofluorescence confirmed corresponding changes at the protein level. In contrast to the down-regulation of type I collagen gene expression, collagenase gene expression was found to be up-regulated severalfold by bFGF. The data suggest that bFGF is capable of regulating collagen and collagenase gene expression divergently in human smooth muscle cells and that the effects appear to be mediated at a pretranslational level.

Cells, Cultured↗

PubMed1995

[Changes of lung function in ex-smokers].

Lung function in 31 ex-smokers, 17 with six to eight and 14 with 11 to 15 years of cigarette smoking, and pair-matched controls were studied. Results showed smoking could cause prolongation of mean through time and partial mean through time in forced expiratory volume scheme, which increased with length of smoking, and multiple abnormal in lung function tests. Lung function could improve apparently after the cease of smoking. It suggested quitting of smoking could prevent lung function from further damage, or reverse the damaged lung function.

Adult↗

PubMed1995

Antibody to ras proteins in patients with colon cancer.

The current study examined sera from 160 colon cancer patients and 60 normal individuals to determine whether antibody to mutated p21 ras protein was present. Studies focused on the aspartic acid substitution at amino acid position 12 (denoted D12), one of the most common mutations in colon adenocarcinoma. IgA antibodies directed against mutated p21 ras-D12 protein were detected in 51 (32%) of 160 colon cancer patients, but only in 1 (2.5%) of 40 normal individuals. The greater incidence of antibody in cancer patients provides presumptive evidence that immunization to the ras proteins occurred as a result of the malignancy. Examination of sera for antibody reactivity to wild-type p21 ras protein (denoted p21 ras-G12) as well as p21 ras proteins bearing the D12, V12, S12, or L61 mutations showed that antibody detected was largely to normal segments of the p21 ras protein. Epitope mapping, using peptide neutralization assays with mutated or normal ras peptides as competitors, demonstrated that in 10 (67%) of 15 sera examined the antibody reactivity to p21 ras-G12 protein was neutralized by peptides near the carboxyl terminus of p21 ras protein, but not by peptides spanning the specific point mutation region. Antibody reactivities correlated with peripheral blood lymphocyte count, but did not correlate with patient age, sex, histology, stage, tumor locus, lymph node metastasis, or serum carcinoembryonic antigen.

Antibodies, Neoplasm↗

PubMed1994

Isolation and structure of cat superfast myosin light chain-2 cDNA and evidence for the identity of its human homologue.

A full-length cDNA clone coding for superfast myosin light chain-2 (MyLC2) was isolated from an expression cDNA library prepared from cat masseter muscle and was fully characterized. The deduced amino acid sequence shares 58% overall identity with limb fast MyLC2, whereas homologies of the latter among higher vertebrates show 90% identity, indicating that superfast MyLC2 has diverged considerably from limb fast MyLC2 during evolution. Superfast MyLC2 cDNA has 89% nucleotide homology and 93% amino acid homology with a published novel human MyLC2 (MYL5), suggesting that MYL5 is a human homologue of the cat superfast MyLC2. Hybridization of a superfast MyLC2 isoform-specific probe reveals that expression of superfast MyLC2 in cat is confined to jaw-closing muscles. In conclusion, the present paper describes for the first time the cloning of a superfast myosin light chain coding sequence.

Amino Acid Sequence↗

PubMed1994

Molecular screening of the glucokinase gene in familial type 2 (non-insulin-dependent) diabetes mellitus.

The glucokinase locus has been implicated by linkage studies in several Caucasian pedigrees with early onset, autosomal dominant diabetes, and mutations have been identified in a large number of these pedigrees. Although mutations have been reported in some pedigrees with late onset Type 2 (non-insulin-dependent) diabetes mellitus, linkage studies of typical familial Type 2 diabetes did not suggest a major role for this locus. Nonetheless, linkage studies were consistent with the hypothesis that mutations of the glucokinase gene were responsible for the pathogenesis of Type 2 diabetes in a minority of pedigrees or one gene in a polygenic disorder. To systematically address this hypothesis, we examined 60 diabetic members of 18 pedigrees ascertained for two or more Type 2 diabetic siblings and eight unrelated diabetic spouses. Initially, the coding regions from each of the 11 glucokinase exons were examined by the sensitive technique of single strand conformation polymorphism analysis to screen for single nucleotide substitutions. Subsequently, we also sequenced each exon from an affected member of the single pedigree in which a glucokinase allele was most likely to segregate with diabetes. Single strand conformation polymorphism analysis detected only three variants, none of which altered the amino acid sequence. No coding or splice site mutations were detected. Likewise, no additional mutations were detected upon direct sequence analysis. However, additional screening of promoter and 3' untranslated regions detected a variant pattern in the untranslated region of exon 10 which appeared to segregate with diabetes and impaired glucose tolerance in one pedigree.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗