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Biomedical subjects

Q Huang

Publications and source records attributed to Q Huang.

At least 37 records · Page 2Linked to original sources
PubMed2004

Detection of the differentially expressed gene IGF-binding protein-related protein-1 and analysis of its relationship to fasting glucose in Chinese colorectal cancer patients.

IGF-binding protein-related protein-1 (IGFBP-rP1) is a member of the IGF axis. In our previous work, we separated cDNA fragments of IGFBP-rP1 from colonic adenocarcinoma and normal mucosa cDNA subtraction libraries. In this study, we compared the expression of IGFBP-rP1 by semi-quantitative RT-PCR and immunohistochemistry among colorectal cancer, adenoma, normal tissue adjacent to cancer site, and normal tissue. Associations between IGFBP-rP1 and plasma glucose were further explored. We found that the mRNA level of IGFBP-rP1 was highest in cancer, moderate in adenoma and tissue adjacent to the cancer site and lowest in normal tissue (P<0.05). A significant difference was found in the immunoreactivity of IGFBP-rP1 between paired normal and cancer tissue (P<0.05). Tumor samples with upregulated expression of IGFBP-rP1 in invading tumor cells showed an increased frequency of metastasis to the lymph node, an increased depth of infiltration and stronger staining of IGFBP-rP1 compared with other samples (P<0.05). The fasting glucose level was significantly correlated with the staining of IGFBP-rP1 in cancer tissue (Spearman's rho=0.4, P<0.000). Thus, we concluded overexpression of IGFBP-rP1 might play an important role in the initiation and promotion of colorectal cancer. IGFBP-rP1 expression may also be associated with fasting glucose level and the presence of diabetes mellitus.

Adenocarcinoma↗
PubMed2003

Charge, orbital and spin ordering phenomena in the mixed valence manganite (NaMn3+(3))(Mn3+(2)Mn4+(2))O12.

Mixed-valence manganites with the ABO3 perovskite structure display a variety of magnetic and structural transitions, dramatic changes of electrical conductivity and magnetoresistance effects. The physical properties vary with the relative concentration of Mn3+ and Mn4+ in the octahedral corner-sharing network, and the proportion of these two cations is usually changed by doping the trivalent large A cation (for example, La3+) with divalent cations. As the dopant and the original cation have, in general, different sizes, and as they are distributed randomly in the structure, such systems are characterized by local distortions that make it difficult to obtain direct information about their crystallographic and physical properties. On the other hand, the double oxides of formula AA'3Mn4O12 contain a perovskite-like network of oxygen octahedra centred on the Mn cations, coupled with an ordered arrangement of the A and A' cations, whose valences control the proportion of Mn3+ and Mn4+ in the structure. The compound investigated in this work, (NaMn3+(3))(Mn3+(2)Mn4+(2))O12, contains an equal number of Mn3+ and Mn4+ in the octahedral sites. We show that the absence of disorder enables the unambiguous determination of symmetry, the direct observation of full, or nearly full, charge ordering of Mn3+ and Mn4+ in distinct crystallographic sites, and a nearly perfect orbital ordering of the Mn3+ octahedra.

Journal Article↗
PubMed2003

Ba2LnSbO6 and Sr2LnSbO6 (Ln = Dy, Ho, Gd) double perovskites: lanthanides in the geometrically frustrating fcc lattice.

Magnetic ground states in solids often arise as a result of a delicate balance between competing factors. One currently active area of research in magnetic materials involves compounds in which long-range magnetic ordering at low temperatures is frustrated by the geometry of the crystalline lattice, a situation known as geometrical magnetic frustration. The number of systems known to display the effects of such frustration is growing, but those that are sufficiently simple from theoretical, chemical, and physical perspectives to allow for detailed understanding remain very few. A search for model compounds in this family has led us to the double perovskites Ba2LnSbO6 and Sr2LnSbO6 (Ln = Dy, Ho, and Gd) reported here. Ba2DySbO6,Ba2HoSbO6,Sr2DySbO6, and Sr2HoSbO6 are structurally characterized by powder neutron diffraction at ambient temperature. The trivalent lanthanides and pentavalent antimony are found to be fully ordered in the double-perovskite arrangement of alternating octahedra sharing corner oxygens. In such a structure, the lanthanide sublattice displays a classical fcc arrangement, an edge-shared network of tetrahedra known to result in geometric magnetic frustration. No magnetic ordering is observed in any of these compounds down to temperatures of 2 K, and in the case of the Dy-based compounds in particular, frustration of the magnetic ordering is clearly present. Lanthanide-based double perovskites are proposed to be excellent model systems for the detailed study of geometric magnetic frustration.

Journal Article↗
PubMed2003

Experimentally induced unilateral tooth loss: expression of type II collagen in temporomandibular joint cartilage.

PURPOSE: We sought to examine possible changes in pattern and concentration of type II collagen in the condylar cartilage and articular disc of the temporomandibular joint (TMJ) in response to unilateral extraction of mandibular teeth in a rabbit model as a means of elucidating the effects of unilateral mastication on the TMJ. METHODS: A total of 12 experimental rabbits were killed either 3 or 6 weeks after the extractions, and 3 additional rabbits without extractions were used as controls. TMJ blocks from both sides of each of the 15 animals were examined for type II collagen via an immunoperoxidase procedure. RESULTS: Anti-type II collagen antibody (Ab) binding was detected mainly in the hypertrophic chondroblast layer of the condylar cartilage of normal rabbits. At 3 weeks after unilateral extraction of teeth, anti-type II collagen Ab binding to the territorial matrix of the hypertrophic chondroblast layer of the condylar cartilage and to the disc was stronger than normal. The increase in Ab binding appeared more dramatic on the nonfunctional side than on the functional side of TMJ. Variations from the normal pattern of anti-type II collagen Ab binding in terms of distribution through the extracellular matrix and fibrillar appearance were also observed. CONCLUSION: The findings suggest that the condylar cartilage and disc adapt to the imbalance induced by unilateral extraction of teeth through chondrocyte repair responses involving collagen II expression that appear to differ between the functional and nonfunctional sides of the TMJ.

Animals↗
PubMed2003

Fourier-transform Raman and infrared spectroscopic analysis of 2-nitro-tetraphenylporphyrin and metallo-2-nitro-tetraphenylporphyrins.

The Fourier-transform Raman (FT-Raman) and infrared (FT-IR) spectra of 2-nitro-tetraphenylporphyrin (2-NO(2)-TPP), nickel-2-nitro-tetraphenylporphyrin (Ni-2-NO(2)-TPP), zinc-2-nitro-tetraphenylporphyrin (Zn-2-NO(2)-TPP) and copper-2-nitro-tetraphenylporphyrin (Cu-2-NO(2)-TPP) were acquired for the first time and carefully assigned and discussed. The effects of a beta-NO(2) group and the influence of the central metal on the molecular symmetry and vibrational spectra of the porphyrin macrocycle were also examined. The bands at 1323-1339, 1516-1526 and 961-971 cm(-1) were attributed to the symmetric and asymmetric stretching vibration of the NO(2) group and to the stretching vibration of the C(beta)-N bond, respectively, which connects the NO(2) group with the beta-carbon of the porphyrin macrocycle. These bands can act as a marker to distinguish beta-NO(2) TPPs from other beta-substituent TPPs. Cu-2-NO(2)-TPP has a C(4nu) molecular symmetry, which is different from those of Ni-2-NO(2)-TPP and Zn-2-NO(2)-TPP, i.e. D(4h).

Organometallic Compounds↗
PubMed2002

Orbital ordering transition in La4Ru2O10.

We report experimental evidence for a full orbital ordering transition in the two-dimensional lanthanum ruthenate La4Ru2O10. The observable consequences of this orbital ordering include the loss of the Ru local moment, a structural distortion which partitions Ru-O bonds into axially oriented short and long sets, a sharp jump in electrical resistivity, and the opening of a spin gap that is visible in neutron scattering experiments. This is a rare example of a discrete orbital ordering transition in a 4d transition metal oxide and demonstrates that orbital effects can have an influence on the properties of layered ruthenates, a family of compounds that notably includes the p-wave superconductor Sr2RuO4 and the field-tuned quantum critical metamagnet Sr3Ru2O7.

Journal Article↗
PubMed2002

Emergent excitations in a geometrically frustrated magnet.

Frustrated systems are ubiquitous, and they are interesting because their behaviour is difficult to predict; frustration can lead to macroscopic degeneracies and qualitatively new states of matter. Magnetic systems offer good examples in the form of spin lattices, where all interactions between spins cannot be simultaneously satisfied. Here we report how unusual composite spin degrees of freedom can emerge from frustrated magnetic interactions in the cubic spinel ZnCr(2)O(4). Upon cooling, groups of six spins self-organize into weakly interacting antiferromagnetic loops, whose directors -- the unique direction along which the spins are aligned, parallel or antiparallel -- govern all low-temperature dynamics. The experimental evidence comes from a measurement of the magnetic form factor by inelastic neutron scattering; the data show that neutrons scatter from hexagonal spin clusters rather than individual spins. The hexagon directors are, to a first approximation, decoupled from each other, and hence their reorientations embody the long-sought local zero energy modes for the pyrochlore lattice.

Journal Article↗
PubMed2002

In vivo mesenchymal cell recruitment by a scaffold loaded with transforming growth factor beta1 and the potential for in situ chondrogenesis.

The objectives of this study were (1) to develop a biphasic implant made of a bioresorbable polymeric scaffold in combination with TGF-beta1-loaded fibrin glue for tissue-engineering applications, and (2) to determine whether the implant made of a polycaprolactone (PCL) scaffold and TGF-beta1-loaded fibrin glue could recruit mesenchymal cells and induce the process of cartilage formation when implanted in ectopic sites. Twenty-four 6-month-old New Zealand White rabbits were used. Scaffolds loaded with various doses of TGF-beta1 in fibrin glue were implanted subcutaneously, intramuscularly, and subperiosteally. The rabbits were killed and implants were removed at 2, 4, and 6 weeks postoperatively. The specimens were subjected to various staining techniques for histological analysis. Light microscopic examination of all specimens revealed that the entire pore space of the scaffolds was filled with various tissues in each group. The entire volume of the scaffolds in the groups loaded with TGF-beta1 and implanted intramuscularly and subcutaneously was populated with mesenchymal cells surrounded with an abundant extracellular matrix and blood vessels. The scaffold loaded with TGF-beta1 and implanted subperiosteally was found to be richly populated with chondrocytes at 2 and 4 weeks and immature bone formation was identified at 6 weeks. We conclude that scaffolds loaded with TGF-beta1 can successfully recruit mesenchymal cells and that chondrogenesis occurred when this construct was implanted subperiosteally.

Animals↗
PubMed2002

Relationship of tumour necrosis factor alpha gene polymorphisms and neuropsychiatric lupus.

Systemic lupus erythematosus (SLE) is a multisystem disorder which appears to be influenced by genetic make-up. In this study we determine allele frequency and genotype distribution of TNFalpha polymorphisms in two populations of SLE patients (with and without neuropsychiatric manifestations) in order to determine whether the rare allele (TNF2) confers susceptibility for neuropsychiatric disease in SLE. Patients with SLE were retrospectively reviewed to determine presence (n = 17) or absence (n = 47) of documented neuropsychiatric manifestations attributable to SLE. The DNA from these patients was extracted from peripheral blood mononuclear cells, and PCR amplification, NcoI enzyme digestion and 10% polyacrylamide gel electrophoresis were performed to define the different TNFalpha alleles. Two alleles were demonstrated, TNF1 (wild-type) and TNF2 (rare type), with three possible genotypes, TNF1,1, TNF1,2 and TNF2,2. A frequency of 24% was found for the TNF2 patients with neuropsychiatric involvement and was not statistically different to a frequency of 28% found in SLE patients without neuropsychiatric manifestations. The TNF-2 allele does not confer susceptibility for neuropsychiatric manifestations in SLE patients.

Adult↗
PubMed2002

Experimentally induced unilateral tooth loss: histochemical studies of the temporomandibular joint.

Occlusal abnormality may contribute to osteoarthrosis of the temporomandibular joint (TMJ). Since mechanical force may induce changes in the extracellular matrix, we tested the hypothesis that unilateral removal of teeth and the resulting unilateral mastication change the content of glycosaminoglycans (GAGs) in the TMJ condyle and disc. Lower-right-side teeth were extracted from 12 adult male rabbits, which were killed 3 or 6 weeks later. Three normal rabbits served as controls. Sections were analyzed for morphological changes and levels of sulfated GAGs in the condyle and disc. Unilateral removal of teeth led to thickening of the condylar cartilage, alterations in the morphology of chondrocyte nuclei in the condylar cartilage and disc, and increases in levels of negatively charged ions in the hypertrophic layer of condylar cartilage. Small differences were observed, after unilateral removal of teeth, between the functional and non-functional sides of the TMJ. The results suggest that in response to mechanical stress, chondrocytes alter sulfated glycosaminoglycan (GAGs) synthesis and degradation rates, resulting in an elevated level of sulfated GAGs in the condylar cartilage.

Animals↗
PubMed2001

The plasticity of dendritic cell responses to pathogens and their components.

Dendritic cells are involved in the initiation of both innate and adaptive immunity. To systematically explore how dendritic cells modulate the immune system in response to different pathogens, we used oligonucleotide microarrays to measure gene expression profiles of dendritic cells in response to Escherichia coli, Candida albicans, and influenza virus as well as to their molecular components. Both a shared core response and pathogen-specific programs of gene expression were observed upon exposure to each of these pathogens. These results reveal that dendritic cells sense diverse pathogens and elicit tailored pathogen-specific immune responses.

Antigen Presentation↗
PubMed2001

Dihedral angles of trialanine in D2O determined by combining FTIR and polarized visible Raman spectroscopy.

We have measured the polarized visible Raman and FTIR spectra of trialanine and triglycine in D(2)O at acid, neutral, and alkaline pD. From the Raman spectra we obtained the isotropic and the anisotropic scattering. A self-consistent spectral analysis of the region between 1550 and 1800 cm(-1) was carried out to obtain the intensities, frequencies, and halfwidths of the respective amide I bands. A model was developed by means of which the intensity ratios of the amide I bands in all spectra and the respective frequency differences were utilized to determine the orientational angle theta between the peptide groups and the strength of excitonic coupling between the corresponding amide I modes. By exploiting results from a recent ab initio study on triglycine (Torii, H; Tasumi, M. J. Raman Spectrosc. 1998, 29, 81), we used these parameters to determine the dihedral angles phi and psi between the peptide groups. Our results show that trialanine adopts a 3(1)-helical structure in D(2)O for all of its three protonation states. The structure is insensitive to the carboxylate protonation and changes only slightly with N-terminal protonation. Triglycine is structurally more heterogeneous in the zwitterionic and the cationic state. Our spectral analysis suggests that 3(1)-helices coexist with right-handed alpha-helical and/or with beta-turn conformations. The N-terminal protonation stabilizes the 3(1)-structure. Our study provides compelling evidence that tripeptides adopt stable conformations in aqueous solution and that they are suitable model systems to investigate the initiation of secondary structure formation.

Alanine↗
PubMed2001

[Establishment of model of aristolochic acid-induced chronic renal interstitial fibrosis in rats].

OBJECTIVE: To study chronic renal interstitial fibrosis induced by aristolochic acid (AA) in animal models. METHODS: Female Wistar rats were divided into two groups: AA group (n = 42) peritoneally injected with AA (5 mg.kg-1.d-1) for 16 weeks and control group (n = 5) peritoneally injected with normal saline (2 ml/d) for 16 weeks. The body weight of rats was taken. At week 8, 12, 16, and 24 six rats were killed in the AA group. The five rats in the control group were killed at week 24. Specimens of lood and urine were taken before the animals were killed. Specimens of renal tissue were taken after the animals were killed. Twenty-four hour urine protein, urine beta 2 microglobulin (beta 2-MG), and renal function were tested regularly. Pathological examination, including tubulo-interstitial area calculation, was made to the renal specimens. RESULTS: The body weight of rats in AA group became significantly lower than that of the control rats after 16 weeks' AA injection (P < 0.01). The blood urea nitrogen (BUN) and serum creatinine (Scr) in AA group increased significantly than those of the control group at the 16th, 20th, and 24th weeks (P < 0.05). Optical microscopy showed tubular-interstitial damage in AA group in 16 weeks. Renal tubular atrophy and multifocal renal interstitial fibrosis were shown in 24 weeks. The area of renal tubule increased and the area of the lumen remarkably decreased at week 16 compared with those in the control group. The area of renal tubule decreased remarkably and the area of renal interstitial greatly in the AA group at week 24. Electrical microscopy showed increase of primary and secondary lysosomes and diasappearence of part of brush border of tubular endothelial cells at week 16, and accumulation of secondary lysosome in cytoplasm at weeks 20 and 24 in the AA group. Histoimmunofluorescence showed that IgG, IgA, IgM, C3, and C1q were negative in the renal tissue of experimental animals. CONCLUSION: Animal models with chronic renal tubuloointerstitial nephropathy induced by aristolochic acid were successfully established. Aristolochic acid may have chronic toxicity to renal tissues, and cause chronic renal interstitial fibrosis in rats.

Animals↗
PubMed2001

p160 Bcr mediates platelet-derived growth factor activation of extracellular signal-regulated kinase in vascular smooth muscle cells.

BACKGROUND: The human Bcr gene was originally identified by its presence in the chimeric Bcr/Abl oncogene, which is causative for chronic myeloblastic leukemia. Because Bcr encodes a serine/threonine protein kinase, we studied its kinase activity and determined the role of Bcr in the PDGF signaling pathway to ERK1/2 activation and DNA synthesis in rat aortic smooth muscle cells (RASMCs). METHODS AND RESULTS: In RASMCs, platelet-derived growth factor-BB (PDGF) stimulated Bcr kinase activity, with a maximum at 1 minute. Because phosphatidylinositol 3'-kinase (PI3-K) is essential for Bcr/Abl leukemogenesis, we evaluated the role of mouse PDGF-beta-receptor binding sites for PI3-K (Y708, Y719) and for phospholipase C-gamma (Y977, Y989) in PDGF-mediated Bcr kinase activation. The mutant PDGF receptor Y708F/Y719F but not Y977F/Y989F showed significantly reduced Bcr kinase activity. To determine the role of Bcr in PDGF-mediated signal transduction events leading to ERK1/2 and its downstream Elk1 transcription activation, wild-type (WT) and kinase-negative (KN) Bcr were transiently expressed in RASMCs. Bcr WT enhanced, whereas Bcr KN inhibited, PDGF-stimulated ERK1/2 and Elk1 transcriptional activity. Overexpression of Bcr also enhanced PDGF-induced Ras/Raf-1 activity and DNA synthesis, but this regulation is independent of the kinase activity of Bcr. Finally, we found that Bcr expression was increased in the neointimal layer after balloon injury of rat carotid artery. CONCLUSIONS: These results demonstrated the importance of Bcr in PDGF-mediated events, such as activation of Ras, Raf-1, ERK1/2, and Elk1, and stimulation of DNA synthesis.

Animals↗
PubMed2001

Crystal structure of alpha-momorcharin in 80% acetonitrile--water mixture.

Crystals of alpha-momorcharin (MMC) were cross-linked and soaked in an 80% acetonitrile--water mixture and X-ray data were collected to 2.2 A resolution. MMC is a ribosome-inactivating protein with a sugar chain on Asn-227. In previous studies, the whole conformation of the sugar chain could not be obtained in the aqueous system. Here the structure of MMC in a low water system is shown to be similar to the native one, but the sugar chain on Asn-227 is defined by the electron density map. Several oxygen atoms of the oligosaccharide formed intramolecular hydrogen bonds to the protein moiety. The conformation of the residues in the active center is similar to that in the aqueous system. Our results show conformational alteration of the tetrasaccharide of MMC in organic media. They indicate that the oligosaccharides are more rigid in organic solvents. X-ray determination in organic media may be used to solve some structures of oligosaccharides linked to glycoproteins.

Acetonitriles↗
PubMed2001

Giant anharmonicity and nonlinear electron-phonon coupling in MgB2: a combined first-principles calculation and neutron scattering study.

First-principles calculations of the electronic band structure and lattice dynamics for the new superconductor MgB (2) are carried out and found to be in excellent agreement with our inelastic neutron scattering measurements. The numerical results reveal that the E(2g) in-plane boron phonons near the zone center are very anharmonic and strongly coupled to the planar B sigma bands near the Fermi level. This giant anharmonicity and nonlinear electron-phonon coupling is key to quantitatively explaining the observed high T(c) and boron isotope effect in MgB (2).

Journal Article↗