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H Qin

Publications and source records attributed to H Qin.

At least 55 records · Page 3Linked to original sources
PubMed1999

Hirudin display on the surface of bacteriophage M13.

Hirudin was fused to the N terminus of M13 minor protein gp3 (197-406) through a linker GGGS by inserting both the hirudin gene and the gp8 signal sequence into the modified phagemid vector pCANTAB 5V to construct pCANTAB 5G8-Hir. The expressed fusion protein was directed by gp8 signal peptide into the periplasm and assembled to the phage particle to form the hirudin-phage. The fusion protein and fusion phage were detected with biotin-thrombin by Western blotting analysis. Antithrombin activity analysis confirmed that the hirudin portion in the fusion protein and fusion phage bear similar native conformation. The successful display of hirudin on the surface of M13 phage laid a sound foundation for the further study on directed evolution of antithrombotic proteins with altered properties.

Antithrombins↗
PubMed1999

[79 cases: a clinical analysis of hoarseness in children].

OBJECTIVE: To research the clinical characters of the hoarseness in children. METHOD: 79 cases are analysed retrospectively. RESULT AND CONCLUSION: Age for this disease is usually 3 years old. People with irritable character are more easy to get it. Vocal nodule is the main cause to chronic hoarseness in children. Conservative treatment is important.

Adolescent↗
PubMed1998

Transcriptional suppression of matrix metalloproteinase-2 gene expression in human astroglioma cells by TNF-alpha and IFN-gamma.

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that function in the turnover of extracellular matrix components during development. In addition, MMPs also contribute to pathological conditions associated with inflammation, angiogenesis, and tumor invasion. A 72-kDa type IV collagenase, also referred to as gelatinase A or MMP-2, has been proposed to potentiate the invasion and metastasis of malignant tumors. In particular, MMP-2 activity has been shown to constitute an important component of human astroglioma invasion. We investigated the influence of various cytokines, both proinflammatory and immunosuppressive, on MMP-2 gene expression in two human astroglioma cell lines (U251-MG and CRT). Our results indicate that the cell lines constitutively express high levels of MMP-2 mRNA, protein, and bioactivity as assessed by ribonuclease protection assay, immunoblotting, and zymography assays, respectively. The proinflammatory cytokines TNF-alpha and IFN-gamma individually can inhibit constitutive MMP-2 expression, and function in an additive manner for near-complete inhibition of MMP-2 expression. Inhibition of MMP-2 mRNA levels by TNF-alpha and IFN-gamma is not due to destabilization of the MMP-2 message; rather, inhibition is mediated at the transcriptional level. Furthermore, TNF-alpha/IFN-gamma inhibition of MMP-2 expression results in decreased invasiveness of the human astroglioma cells through an extracellular matrix. These results raise the possibility that TNF-alpha and IFN-gamma may have beneficial effects in attenuating astroglioma invasive properties.

Astrocytes↗
PubMed1998

Design and synthesis of analogs of vitamin E: antiproliferative activity against human breast adenocarcinoma cells.

Analogs of alpha-tocopherol (vitamin E; compounds 3-9) have been synthesized and tested for their antiproliferative activity using the human breast cancer cell line, MCF7. Compounds 6-9 were synthesized from a common symthom, rac-Trolox (14) and are soluble/miscible at physiological pH. Compounds 4, 8, and 9 were found to have antiproliferative activity at micromolar concentrations.

Adenocarcinoma↗
PubMed1998

Q-band resonance Raman spectra of oxidized and reduced mitochondrial bc1 complexes.

Recently published crystallographic studies of mitochondrial bc1 complexes have stimulated renewed interest in the active site architecture of these important integral membrane proteins. We present resonance Raman spectra obtained via variable excitation within the heme Q-band from samples poised in several different net redox states. Appropriate subtraction and polarization analysis allows the vibrational behavior of the individual heme bL,bH, and c1 sites to be assessed. The spectra of the b hemes are particularly noteworthy. They exhibit evidence for a protonation equilibrium involving heme axial ligands and reveal a marked structural heterogeneity at the heme bH site that most likely involves nonplanar distortions of the macrocycle. The possible implications of these findings for heme functionality are discussed.

Animals↗
PubMed1998

Diversity of C-linked neoglycopeptides for the exploration of subsite-assisted carbohydrate binding interactions.

Diversity of alpha-galactose based C-linked neoglycopeptides (1b, 2b, 3c, 4d, and 5d) has been developed to explore the importance of subsite-assisted carbohydrate binding interactions. Deprotected C-linked neoglycopeptides (1b, 2b, 3c, 4d, and 5d) were synthesized and tested in competitive inhibition assays using a model enzyme-linked lectin (e.g., Maclura pomifera). Compound 2b, with two alpha-galactoside units on the side chain of the lysine residue of the dipeptide backbone, exhibited a remarkable effect with a 2.82-fold increase in its inhibitory properties (IC50 1.48 mM) in comparison to 1b (IC50 4.18 mM).

Binding Sites↗
PubMed1998

Overexpression of human copper, zinc-superoxide dismutase (SOD1) prevents postischemic injury.

Superoxide and superoxide-derived oxidants have been hypothesized to be important mediators of postischemic injury. Whereas copper, zinc-superoxide dismutase, SOD1, efficiently dismutates superoxide, there has been controversy regarding whether increasing intracellular SOD1 expression would protect against or potentiate cellular injury. To determine whether increased SOD1 protects the heart from ischemia and reperfusion, studies were performed in a newly developed transgenic mouse model in which direct measurement of superoxide, contractile function, bioenergetics, and cell death could be performed. Transgenic mice with overexpression of human SOD1 were studied along with matched nontransgenic controls. Immunoblotting and immunohistology demonstrated that total SOD1 expression was increased 10-fold in hearts from transgenic mice compared with nontransgenic controls, with increased expression in both myocytes and endothelial cells. In nontransgenic hearts following 30 min of global ischemia a reperfusion-associated burst of superoxide generation was demonstrated by electron paramagnetic resonance spin trapping. However, in the transgenic hearts with overexpression of SOD1 the burst of superoxide generation was almost totally quenched, and this was accompanied by a 2-fold increase in the recovery of contractile function, a 2.2-fold decrease in infarct size, and a greatly improved recovery of high energy phosphates compared with that in nontransgenic controls. These results demonstrate that superoxide is an important mediator of postischemic injury and that increasing intracellular SOD1 dramatically protects the heart from this injury. Thus, increasing intracellular SOD1 expression may be a highly effective approach to decrease the cellular injury that occurs following reperfusion of ischemic tissues.

Animals↗
PubMed1998

Antigen mimicry by an anti-idiotypic antibody single chain variable fragment.

For the therapy of cancer patients whose disease is positive for Carcinoembryonic Antigen (CEA), we developed an active specific immunotherapy based on the idiotypic network. The anti-idiotype monoclonal antibody (mAb), 3H1 was generated by immunization of mice with the anti-CEA mAb, 8019. 3H1 mimics CEA both functionally and structurally and acts as a surrogate for CEA. To define the minimum structural requirements for antigen mimicry by 3H1, we constructed plasmid vectors for expression of single chain Fv (scFv) variants of 3H1 in Escherichia coli. Variable heavy (VH) and variable light (VL) chain domains of 3H1 were linked by a 15 amino acid linker (Ln), (Gly4Ser)3 in two constructs, VH-Ln-VL and VL-LnVH. Ln was omitted in two constructs, VH-VL and VL-VH. Each of the scFv constructs has a tag of six His [(His)6 tag] for purification by metal chelate affinity chromatography and detection by enzyme-linked immunoabsorbent assay (ELISA). Comparisons of the binding of 8019 to purified scFv proteins by ELISA and immunoblot experiments showed that only VH-Ln-VL had significant activity. VH-Ln-VL also showed maximum inhibition of binding of 8019 to CEA. Immunization of mice with naked VH-Ln-VL and VH-Ln-VL conjugated to keyhole limpet hemocyanin induced anti-CEA antibodies in mouse sera. Sera from immunized mice inhibited the binding of 8019 to 3H1 as well as CEA. Induction of anti-CEA antibodies in the immunized mice was confirmed by flow cytometric analysis using CEA positive MC-38cea cells. These results demonstrate that for antigen mimicry of 3H1 scFv, the presence of Ln is necessary and the domain order should be VH followed by VL.

Animals↗
PubMed1998

CTLs specific for bcr-abl joining region segment peptides fail to lyse leukemia cells expressing p210 bcr-abl protein.

The aim of the current study was to determine whether immunization with synthetic peptides corresponding to the joining region segment of p210 bcr-abl chimeric protein can elicit CD8+ cytotoxic T lymphocytes (CTLs) capable of specifically lysing leukemia cells. BALB/c mice were immunized with peptides identical to the joining region segment of p210 bcr-abl protein. Class I major histocompatibility complex (MHC)-restricted bcr-abl peptide-specific CD8+ CTLs were elicited. The CTL clones were H-2 Kd restricted and specifically recognized a nonamer peptide of the combined sequence of bcr-abl amino acids but neither bcr nor abl amino acid sequence alone. Despite specificity and substantial lytic potential against syngeneic cell line incubated with exogenously supplied peptides, the bcr-abl peptide-specific CTLs failed to lyse syngeneic murine leukemia cells expressing human p210 bcr-abl protein containing the same bcr-abl joining region peptide sequence. Similarly, the bcr-abl peptide-specific CTLs did not lyse human bcr-abl-positive chronic myelogenous leukemia cells expressing murine class I MHC antigen (i.e., K562 cells infected with vaccinia virus expressing H-2 Kd). The appropriateness of the joining region segment of bcr-abl protein to serve as a T cell target depends upon whether that segment is presented by class I MHC in a concentration high enough to stimulate CTLs. The current experiments using murine peptide-specific CTLs could not establish that the joining region of bcr-abl protein is processed and presented by class I MHC antigen-processing pathway, but the possibility was not ruled out. Alternative models and/or strategies are necessary.

Amino Acid Sequence↗
PubMed1998

[Synthesis and antiinflammatory activity of 2-(E)-(4-hydroxy-3-methoxybenzylidene)-5-(N-substituted aminomethyl) cyclopentanones].

In search for new antiinflammatory agents, a series of 2-(E)-(4-hydroxy-3-methoxybenzylidene)-5-(N-substituted aminomethyl) cyclopentanones was synthesized via Stork reaction, Mannich reaction and amine exchange reaction. All of the fifteen target compounds were characterized by spectral analysis and elemental analysis. Preliminary pharmacological tests showed that several target compounds exerted appreciable effect on xylene-induced ear edema in mice and that alteration of the substituents of anilines showed significant influence on antiinflammatory potency.

Animals↗
PubMed1998

[Synthesis and antiinflammatory activity of 2-(E)-benzylidene-5-(N-substituted aminomethyl) cyclopentanones].

Nineteen kinds of 2-(E)-benzylidene-5-(N-substituted aminomethyl) cyclopentanones were synthesized via Mannich reaction or amine exchange reaction and identified spectrometrically. One compound exhibited significant antiinflammatory activity, showing obvious inhibitory effect on xylene-induced mice ear swelling, carrageenin-induced rats paw edema and increased capillary permeability induced with acetic acid in mice. Its ED50 values in these inflammatory models were calculated to be 67.8 mg.kg-1, 25.3 mg.kg-1 and 41.8 mg.kg-1 respectively, nearly equal to those of ibuprofen and aspirin.

Animals↗
PubMed1998

[Effects of polysaccharide of Polygala aureocauda on the immunnity functions of normal mouse].

The effects of polysaccharide of polygala aureocauda on the immunity functions of the normal mouse were researched by the tests of clearing away carbon granules, hemolysin antibodies production and lymphocyte transformation. The results showed that the polysaccharide of polygala aureocauda Dunn. (PADTP) could strengthen the phagocytosis of the single nucleus phagocytes, promote the production of the antibodies, and raise the transformable rate of the lympocytes. That proved the PADTP could strengthen immunity function of the normal mouse.

Adjuvants, Immunologic↗
PubMed1997

The 3'-end of the human beta-actin gene enhances activity of the beta-actin expression vector system: construction of improved vectors.

The human beta-actin promoter has been widely used to drive expression of genes of interest in mammalian cell lines and transgenic mice. The original form of the human beta-actin expression vector contains upstream sequences, 5'UTR (untranslated region) and intron 1 from the beta-actin gene linked to a three restriction site polylinker and SV40 (Simian Virus 40) 3'UTR. We have modified this vector now to contain the highly conserved beta-actin 3'UTR plus flanking region which replaces the SV40 sequences. An additional modification has removed the mRNA peripheral localization sequences present in the beta-actin 3'UTR. The new vectors also contain an improved polylinker. The activity of these two new vectors has been compared with that of the original vector and that of a vector using the popular cytomegalovirus (CMV) promoter. Mouse C2 myoblasts were transfected with each vector driving expression of enhanced green fluorescent protein (EGFP) and analyzed for EGFP mRNA levels. We find that both new vectors drive twice the level of mRNA accumulation of the original vector and over 30-times that of the CMV promoter. This suggests that these new vectors will provide a substantial elevation in levels of expression by virtue of inclusion of the beta-actin 3'UTR plus flanking region.

Actins↗
PubMed1997

Synthesis of bombesin analogues for radiolabeling with rhenium-188.

BACKGROUND: Gastrin-releasing peptide receptors (GRPR) are overexpressed in small cell lung carcinoma and some other human cancers. Small molecule peptides with antagonistic activities toward these receptors are potential radiotherapeutic agents. METHODS: A 7-amino acid analogue of bombesin (BBN) was synthesized through solid-phase techniques. The peptide was conjugated to trisuccin prior to cleavage from the resin. The conjugate was hydrogenated to remove the hydroxamate-protecting benzyl groups followed by purification through reversed-phase high performance liquid chromatography (RP-HPLC). Rhenium-188 (188Re)-labeling of the trisuccin-peptide conjugate was performed by a SnCl2-reduced radioisotope and the labeled product was purified by RP-HPLC. The labeled conjugate was incubated with BNR-11 (3T3 mouse fibroblast cells stably transfected with murine GRPR) and PC-3 human prostate carcinoma GRPR positive cells. The nonradioactive peptide analogue was used as a competitive inhibitor and 125I-[Tyr4]-BBN was used as a positive control. RESULTS: Solid-phase and solution phase synthesis afforded the conjugates of the hydroxamate ligand trisuccin with the 7-amino acid BBN analogue. The molecules differed by either a direct attachment of the trisuccin to the peptide (TrisBBN) or connection through a 6-carbon linker (TrisC6BBN). The overall yield for each synthesis was approximately 20%. Both conjugates showed the correct molecular weights on mass spectroscopy. Radiolabeling of the conjugates with 188Re were performed in > or = 90% yield. Cell-binding assays performed with BNR-11 (TrisBBN and TrisC6BBN) and PC-3 (TrisBBN) cell lines resulted in positive binding. CONCLUSIONS: The synthesis and radiolabeling of Tris-BBN conjugates with 188Re were shown to be feasible. The yields of chemical syntheses and radiolabeling and positive binding of the radiolabeled conjugates to GRPR-positive tumor cells reveal promise in the use of these molecules for cancer imaging and therapy. More work is needed and is in progress to optimize the cell-binding properties.

3T3 Cells↗
PubMed1997

Maternal menstrual history and small-for-gestational-age births in a population-based Chinese birth cohort.

The relationship between maternal menstrual history and small-for-gestational-age (SGA) births is examined in a population-based birth cohort of 5291 mothers with singleton births and 28 completed gestational weeks in Qingdao, China, in 1992. Multivariate analyses suggest that the length of the menstrual cycle and age at menarche had independent effects on SGA after controlling for sex of the infant, physical size of the mother, blood pressure at the first antenatal visit, parity, gestational week at the first antenatal visit, number of antenatal visits, number of previous spontaneous abortions and maternal educational attainment and occupation. The relative risk (RR) of SGA among thin mothers (BMI < = 21) is 1.63 (95% confidence interval (CI) 1.16-2.29) if the mother's menarche started after 14 years (reference to < = 14 years), 1.75 (95% CI 0.96-3.20) if the mother's menstrual cycle was 29-30 days and 2.92 (95% CI 1.42-6.03) if the menstrual cycle > = 31 days ( < = 28 as a reference category for both). Among normal weight mothers (BMI 21-24), only a menstrual cycle equal or longer than 31 days still had a significant effect on SGA (RR 2.17, 95% CI 1.18-4.08), and among fat mothers no significant effects were observed. The results encourage further evaluation of the association between maternal menstrual background and fetal development among other ethnic populations and exploration of the possible biological mechanisms behind this relationship.

Adult↗
PubMed1997

Regulation of human interstitial collagenase (matrix metalloproteinase-1) promoter activity by fibroblast growth factor.

Basic fibroblast growth factor (bFGF) is a pleiotropic factor that is implicated in tissue remodeling. The growth factor is capable of up-regulating the expression of the interstitial collagenase (matrix metalloproteinase-1 or MMP-1) gene. In this study, the full-length human MMP-1 promoter, spanning 4.3 kb, was sequenced and the regulatory control of its activity by bFGF was examined in NIH3T3 fibroblasts. Several regulatory sequences, including five activator protein-1 (AP-1), five activator protein-2 (AP-2), five glucocorticoid-response elements and multiple ets/polyoma enhancer-binding 3 elements, were identified. Deletion constructs were prepared and transiently transfected into fibroblast cultures incubated with and without bFGF. The results showed that bFGF enhanced the activity of the deletion promoter fragments and the full-length MMP-1 promoter by sixfold or more in the cell cultures. Stimulation of the MMP-1 promoter activity by bFGF was reflected in substantial increase of the collagenase mRNA levels. A bFGF-responsive element appeared to be the AP-1 consensus sequence. Mutation of the first AP-1 site resulted in major reduction of the basal level of the MMP-1 promoter activity, supporting the notion that the AP-1 consensus sequence is essential for the constitutive expression of the MMP-1 gene. Furthermore, bFGF induction of the activity of the promoter constructs containing a mutant AP-1 site was essentially absent, suggesting that the regulatory element is necessary for the induction of the promoter activity by the growth factor. Thus, bFGF up-regulates MMP-1 gene expression in NIH3T3 fibroblasts via induction of its promoter activity that is dependent on an AP-1 consensus sequence.

3T3 Cells↗
PubMed1997

TGF-beta suppresses IFN-gamma induction of class II MHC gene expression by inhibiting class II transactivator messenger RNA expression.

Recently, a non-DNA binding protein, class II transactivator (CIITA), has been shown to be required for constitutive and IFN-gamma-inducible class II MHC transcription. The cytokine TGF-beta inhibits IFN-gamma-induced class II MHC expression at the transcriptional level. In this study, we provide evidence that TGF-beta blocks IFN-gamma-induced CIITA mRNA accumulation. TGF-beta down-regulates class II MHC and CIITA mRNA accumulation in human astroglioma and fibrosarcoma cell lines, but TGF-beta does not destabilize the CIITA message, suggesting an effect at the transcriptional level. In cells that stably overexpressed CIITA, leading to a constitutive class II MHC-positive phenotype, the inhibitory effect of TGF-beta on class II MHC was abrogated, but the cells remained responsive for expression of TGF-beta-inducible genes. Cell lines that possessed defects in TGF-beta signaling also became refractory to inhibition of IFN-gamma-induced CIITA and class II MHC expression. Our data indicate that TGF-beta suppresses IFN-gamma-induced class II MHC expression by inhibiting accumulation of CIITA mRNA.

Astrocytoma↗