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Xiaohua Huang

Publications and source records attributed to Xiaohua Huang.

At least 19 recordsLinked to original sources
PubMed2006

Fibronectin EIIIA splicing variant: a useful contribution to forensic wounding interval estimation.

A fibronectin splicing variant, Fn containing an extra type III domain (EIIIA in rat, ED1 or EDA in human) has recently attracted more attention because of its sensitive response in injury of adult tissue. The characteristic that this form is absent in adult tissue while it is commonly expressed in fetal tissues and injured adult tissue is useful in estimation of injury interval in forensic science. The regulation of fibronectin splicing was studied by immunohistochemistry by using monoclonal antibody to EIIIA on sections from paraffin embedded rat skin sample after contusion. The results indicated that epidermic cells and hair follicle epithelium of rat skin were found positive staining at 6h after injury, and the color became darker with prolonged wounding time. Based on the above result, we invented a type of test paper assayed for EIIIA-Fn splicing variant by using immune colloidal gold technique. After dipping one end of test paper in the supernatant fluid of tissue homogenates of injury skin for few minutes, detecting line could be found. It showed that all experimental injured samples revealed positive staining; the darkness of positive staining was dependent on the injury time, while control normal skin cannot found positive staining. It is concluded that there is a close relationship between the expression of EIIIA-Fn splicing variant and wounding interval, and that the gold-labeled test paper can be useful in distinguishing ante- and post-mortem injury, and in estimation of wounding interval in forensic science.

Alternative Splicing↗
PubMed2006

Identification of HIV-1 Tat peptides for future therapeutic angiogenesis.

Therapeutic angiogenesis represents a novel approach to treat critical limb ischemia when revascularization is no more an option. The clinical use of the vascular endothelial growth factor is questioned, because of its side effects. This study was designed to identify and characterize human immunodeficiency virus type 1 (HIV-1) Tat-derived peptides based on their pro-angiogenic properties. A series of Tat-derived peptides were synthesized containing mutations in the basic domain. To minimize side effects Tat peptides were selected exerting no effects on the proteasome and on the viability of human umbilical vein endothelial cells (HUVEC). Tatpep5, 15, and 16 increased the endogenous levels of the pro-angiogenic transcription factors c-Jun and SP-1 as well as the production of the plasminogen activator inhibitor-1 (PAI-1) by HUVEC. A significant induction of endothelial cell invasion was observed upon treatment of HUVEC with Tat peptides. In addition, selected Tat peptides induced tube formation by HUVEC as visualized and quantified in a Matrigel matrix. Our data demonstrate that the selected Tat peptides fulfill essential criteria for pro-angiogenic substances. They represent the basis for the development of novel pro-angiogenic drugs for future therapeutic angiogenesis, which might be applied for treatment of unreconstructible critical limb ischemia.

Angiogenesis Inducing Agents↗
PubMed2006

Cancer cell imaging and photothermal therapy in the near-infrared region by using gold nanorods.

Due to strong electric fields at the surface, the absorption and scattering of electromagnetic radiation by noble metal nanoparticles are strongly enhanced. These unique properties provide the potential of designing novel optically active reagents for simultaneous molecular imaging and photothermal cancer therapy. It is desirable to use agents that are active in the near-infrared (NIR) region of the radiation spectrum to minimize the light extinction by intrinsic chromophores in native tissue. Gold nanorods with suitable aspect ratios (length divided by width) can absorb and scatter strongly in the NIR region (650-900 nm). In the present work, we provide an in vitro demonstration of gold nanorods as novel contrast agents for both molecular imaging and photothermal cancer therapy. Nanorods are synthesized and conjugated to anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies and incubated in cell cultures with a nonmalignant epithelial cell line (HaCat) and two malignant oral epithelial cell lines (HOC 313 clone 8 and HSC 3). The anti-EGFR antibody-conjugated nanorods bind specifically to the surface of the malignant-type cells with a much higher affinity due to the overexpressed EGFR on the cytoplasmic membrane of the malignant cells. As a result of the strongly scattered red light from gold nanorods in dark field, observed using a laboratory microscope, the malignant cells are clearly visualized and diagnosed from the nonmalignant cells. It is found that, after exposure to continuous red laser at 800 nm, malignant cells require about half the laser energy to be photothermally destroyed than the nonmalignant cells. Thus, both efficient cancer cell diagnostics and selective photothermal therapy are realized at the same time.

Antibodies, Monoclonal↗
PubMed2006

Effect of Tris on catalytic activity of MP-11.

The effect of tris(hydroxymethyl)aminomethane (Tris) on the catalytic activity and microstructure of heme undecapeptide, microperoxidase-11 (MP-11) in the aqueous solution was investigated using cyclic voltammetry, circular dichroism (CD) spectroscopy, UV-vis absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found for the first time that Tris would inhibit the catalytic activity and electrochemical reaction of MP-11 at the glassy carbon (GC) electrode. This is mainly due to the fact that Tris would induce more alpha-helix and beta-turn conformations from the random coil conformation of MP-11, cause the asymmetric split-up in the Soret band region of MP-11, increase the non-planarity of the heme of MP-11, and change the electron densities of N, O and S atoms of MP-11. Meanwhile, It was found that the electrochemical reaction of MP-11 with Tris at GC electrode is diffusion-controlled, and the diffusion coefficient of MP-11 and the rate constant for the heterogeneous electron transfer of MP-11 in the presence of Tris are decreased by 19% and 16%, respectively. Further experiments showed that the electrocatalytic current of MP-11 on the reduction of H2O2 is decreased by about 25% after the addition of Tris to the MP-11 solution.

Catalysis↗
PubMed2006

[Grafting and characterization of poly (ethylene glycol) on polysulfone sheets].

Grafting of poly (ethylene glycol) (PEG) on the surface of polysulfone (PSF) sheets by simultaneous or sequential UV irradiation with 4-azidobenzoic acid as the photocoupler was carried out. Water contact angle measurements showed that there was a great improvement of hydrophilicity on the grafted surface. X-ray photoelectron spectroscopy suggested that the area covered by PEG be 77.3% and 41.9% respectively after grafting by simultaneous and sequential pathways. With atomic force microscope (AFM), obvious difference in the shape and the phase mode was observed between surfaces of PEG-g-PSF sheets made by these two pathways. Evidences implied that simultaneous pathway would produce a branched PEG layer on the surface, while sequential pathway was coupled with a "pan-cake" PEG layer on it. This study provides the foundation for further advancement in tethering brush-like PEG on PSF hollow fiber membranes.

Azides↗
PubMed2005

Selective laser photo-thermal therapy of epithelial carcinoma using anti-EGFR antibody conjugated gold nanoparticles.

Efficient conversion of strongly absorbed light by plasmonic gold nanoparticles to heat energy and their easy bioconjugation suggest their use as selective photothermal agents in molecular cancer cell targeting. Two oral squamous carcinoma cell lines (HSC 313 and HOC 3 Clone 8) and one benign epithelial cell line (HaCaT) were incubated with anti-epithelial growth factor receptor (EGFR) antibody conjugated gold nanoparticles and then exposed to continuous visible argon ion laser at 514nm. It is found that the malignant cells require less than half the laser energy to be killed than the benign cells after incubation with anti-EGFR antibody conjugated Au nanoparticles. No photothermal destruction is observed for all types of cells in the absence of nanoparticles at four times energy required to kill the malignant cells with anti-EGFR/Au conjugates bonded. Au nanoparticles thus offer a novel class of selective photothermal agents using a CW laser at low powers. The potential of using this selective technique in molecularly targeted photothermal therapy in vivo is discussed.

Antibodies, Monoclonal↗
PubMed2005

Gold nanoparticles: catalyst for the oxidation of NADH to NAD(+).

Nicotinamide adenine dinucleotide is an important coenzyme involved in the production of ATP, the fuel of energy, in every cell. It alternates between the oxidized form NAD(+) and the reduced form dihydronicotinamide adenine dinucleotide (NADH) and serves as a hydrogen and electron carrier in the cellular respiratory processes. In the present work, the catalytic effect of gold nanoparticles on the oxidization of NADH to NAD(+) was investigated. The addition of gold nanoparticles was found to quench the NADH fluorescence intensities but had no effect on the fluorescence lifetime. This suggested that the fluorescence quenching was not due to coupling with the excited state, but due to changing the ground state of NADH. The intensity of the 340 nm absorption band of NADH was found to decrease while that of the 260 nm band of NAD(+) was found to increase as the concentration of gold nanoparticles increased. This conversion reaction was further supported by nuclear magnetic resonance and mass spectroscopy. The effect of the addition of NADH was found to slightly red shift and increase the intensity of the surface plasmon absorption band of gold nanoparticles at 520 nm. This gives a strong support that the conversion of NADH to NAD(+) is occurring on the surface of the gold nanoparticles, i.e. NADH is surface catalyzed by the gold nanoparticles. The catalytic property of this important reaction might have important future applications in biological and medical fields.

Catalysis↗
PubMed2005

Novel curcumin- and emodin-related compounds identified by in silico 2D/3D conformer screening induce apoptosis in tumor cells.

BACKGROUND: Inhibition of the COP9 signalosome (CSN) associated kinases CK2 and PKD by curcumin causes stabilization of the tumor suppressor p53. It has been shown that curcumin induces tumor cell death and apoptosis. Curcumin and emodin block the CSN-directed c-Jun signaling pathway, which results in diminished c-Jun steady state levels in HeLa cells. The aim of this work was to search for new CSN kinase inhibitors analogue to curcumin and emodin by means of an in silico screening method. METHODS: Here we present a novel method to identify efficient inhibitors of CSN-associated kinases. Using curcumin and emodin as lead structures an in silico screening with our in-house database containing more than 10(6) structures was carried out. Thirty-five compounds were identified and further evaluated by the Lipinski's rule-of-five. Two groups of compounds can be clearly discriminated according to their structures: the curcumin-group and the emodin-group. The compounds were evaluated in in vitro kinase assays and in cell culture experiments. RESULTS: The data revealed 3 compounds of the curcumin-group (e.g. piceatannol) and 4 of the emodin-group (e.g. anthrachinone) as potent inhibitors of CSN-associated kinases. Identified agents increased p53 levels and induced apoptosis in tumor cells as determined by annexin V-FITC binding, DNA fragmentation and caspase activity assays. CONCLUSION: Our data demonstrate that the new in silico screening method is highly efficient for identifying potential anti-tumor drugs.

Annexin A5↗
PubMed2005

Use of tunable ligands allows for intermolecular Pd-catalyzed C--O bond formation.

Bulky biaryl phosphine ligands facilitate Pd-catalyzed C-O coupling reactions of aryl halides with primary and secondary alcohols by promoting reductive elimination at the expense of beta-hydride elimination. The key to their success is the ability to match the size of the ligand to that of the combination of substrates. The efficient coupling of a number of unactivated aryl chlorides and bromides with cyclic and acyclic secondary alcohols was achieved. This included the coupling of allylic alcohols for the first time in a Pd-catalyzed coupling process.

Alcohols↗
PubMed2005

Surface plasmon resonance scattering and absorption of anti-EGFR antibody conjugated gold nanoparticles in cancer diagnostics: applications in oral cancer.

Gold nanoparticles with unique optical properties may be useful as biosensors in living whole cells. Using a simple and inexpensive technique, we recorded surface plasmon resonance (SPR) scattering images and SPR absorption spectra from both colloidal gold nanoparticles and from gold nanoparticles conjugated to monoclonal anti-epidermal growth factor receptor (anti-EGFR) antibodies after incubation in cell cultures with a nonmalignant epithelial cell line (HaCaT) and two malignant oral epithelial cell lines (HOC 313 clone 8 and HSC 3). Colloidal gold nanoparticles are found in dispersed and aggregated forms within the cell cytoplasm and provide anatomic labeling information, but their uptake is nonspecific for malignant cells. The anti-EGFR antibody conjugated nanoparticles specifically and homogeneously bind to the surface of the cancer type cells with 600% greater affinity than to the noncancerous cells. This specific and homogeneous binding is found to give a relatively sharper SPR absorption band with a red shifted maximum compared to that observed when added to the noncancerous cells. These results suggest that SPR scattering imaging or SPR absorption spectroscopy generated from antibody conjugated gold nanoparticles can be useful in molecular biosensor techniques for the diagnosis and investigation of oral epithelial living cancer cells in vivo and in vitro.

Antigen-Antibody Complex↗
PubMed2005

Consequences of COP9 signalosome and 26S proteasome interaction.

The COP9 signalosome (CSN) occurs in all eukaryotic cells. It is a regulatory particle of the ubiquitin (Ub)/26S proteasome system. The eight subunits of the CSN possess sequence homologies with the polypeptides of the 26S proteasome lid complex and just like the lid, the CSN consists of six subunits with PCI (proteasome, COP9 signalosome, initiation factor 3) domains and two components with MPN (Mpr-Pad1-N-terminal) domains. Here we show that the CSN directly interacts with the 26S proteasome and competes with the lid, which has consequences for the peptidase activity of the 26S proteasome in vitro. Flag-CSN2 was permanently expressed in mouse B8 fibroblasts and Flag pull-down experiments revealed the formation of an intact Flag-CSN complex, which is associated with the 26S proteasome. In addition, the Flag pull-downs also precipitated cullins indicating the existence of super-complexes consisting of the CSN, the 26S proteasome and cullin-based Ub ligases. Permanent expression of a chimerical subunit (Flag-CSN2-Rpn6) consisting of the N-terminal 343 amino acids of CSN2 and of the PCI domain of S9/Rpn6, the paralog of CSN2 in the lid complex, did not lead to the assembly of an intact complex showing that the PCI domain of CSN2 is important for complex formation. The consequence of permanent Flag-CSN2 overexpression was de-novo assembly of the CSN complex connected with an accelerated degradation of p53 and stabilization of c-Jun in B8 cells. The possible role of super-complexes composed of the CSN, the 26S proteasome and of Ub ligases in the regulation of protein stability is discussed.

Animals↗
PubMed2004

Ubiquitin-dependent degradation of Id1 and Id3 is mediated by the COP9 signalosome.

Recently, evidence is accumulating pointing to a function of the COP9 signalosome (CSN) in regulation of ubiquitination by specific ubiquitin ligases. Here, we demonstrate by mammalian two-hybrid analysis that the transcriptional regulators and substrates of the ubiquitin system Id1 and Id3, but not Id2 and Id4, bind to the CSN subunit CSN5. Pull-down experiments revealed that Id3 physically interacts with the CSN complex. Additional far Western and pull-down studies with Id3 support our two-hybrid data and show that the transcription regulator can bind to CSN5 and CSN7. Recombinant Id3 is not phosphorylated by the CSN-associated kinases CK2 and PKD. However, it inhibits c-Jun and CSN2 phosphorylation by the isolated CSN complex and by the recombinant CK2. The inhibitors of CSN associated kinases, curcumin and emodin, significantly induce ubiquitination and proteasome-dependent degradation of transiently expressed Id3 in HeLa cells. Proteasome-dependent degradation of endogenous Id1 in HeLa cells is also stimulated by treatment with curcumin or emodin. Ubiquitination of Id3 is shown directly by cotransfection of HeLa cells with Id3 and His-ubiquitin cDNA. Curcumin increased Id3-ubiquitin conjugate formation, as shown by Western blotting and His-pull-downs. In addition, overexpression of CSN2 leads to stabilization of Id3 protein. On the basis of these data, it is speculated that CSN-mediated phosphorylation inhibits ubiquitination of Id1 and Id3.

Animals↗
PubMed2003

The first general palladium catalyst for the Suzuki-Miyaura and carbonyl enolate coupling of aryl arenesulfonates.

The first general method for the palladium-catalyzed Suzuki-Miyaura and carbonyl enolate coupling of unactivated aryl arenesulfonates was developed utilizing XPhos, 1, and Pd(OAc)2. This is of significant interest because aryl tosylates and aryl benzenesulfonates are more easily handled and considerably less expensive than aryl triflates. This catalyst system effects the coupling of a variety of aryl, heteroaryl, and extremely hindered arylboronic acids with different aryl tosylates, under mild conditions. The same catalyst was employed in the first carbonyl enolate coupling of aryl arensulfonates.

Benzenesulfonates↗
PubMed2003

Expanding Pd-catalyzed C-N bond-forming processes: the first amidation of aryl sulfonates, aqueous amination, and complementarity with Cu-catalyzed reactions.

The first general method for the Pd-catalyzed amination of aryl tosylates and benzenesulfonates was developed utilizing ligand 1, which belongs to a new generation of biaryl monophosphine ligands. In addition, the new catalyst system for the first time enables amidation of aryl arenesulfonates and aqueous amination protocols that do not necessitate the use of cosolvents. The substrate scope has been significantly expanded to include aryl halides containing primary amides and free carboxylic acid groups. In the case of multifunctional substrates, the Pd-catalyzed amination can provide selectivity that is complementary to the Cu-catalyzed C-N bond-forming processes.

Amides↗
PubMed2003

Protein kinase CK2 and protein kinase D are associated with the COP9 signalosome.

The COP9 signalosome (CSN) purified from human erythrocytes possesses kinase activity that phosphoryl ates proteins such as c-Jun and p53 with consequence for their ubiquitin (Ub)-dependent degradation. Here we show that protein kinase CK2 (CK2) and protein kinase D (PKD) co-purify with CSN. Immunoprecipitation and far-western blots reveal that CK2 and PKD are in fact associated with CSN. As indicated by electron microscopy with gold-labeled ATP, at least 10% of CSN particles are associated with kinases. Kinase activity, most likely due to CK2 and PKD, co-immuno precipitates with CSN from HeLa cells. CK2 binds to DeltaCSN3(111-403) and CSN7, whereas PKD interacts with full-length CSN3. CK2 phosphorylates CSN2 and CSN7, and PKD modifies CSN7. Both CK2 and PKD phosphorylate c-Jun as well as p53. CK2 phosphoryl ates Thr155, which targets p53 to degradation by the Ub system. Curcumin, emodin, DRB and resveratrol block CSN-associated kinases and induce degradation of c-Jun in HeLa cells. Curcumin treatment results in elevated amounts of c-Jun-Ub conjugates. We conclude that CK2 and PKD are recruited by CSN in order to regulate Ub conjugate formation.

Adenosine Triphosphate↗
PubMed2003

Comparative analysis of conventional Papanicolaou tests and a fluid-based thin-layer method.

CONTEXT: A fluid-based, direct-to-vial method of thin-layer gynecologic cytology (ThinPrep Pap Test) is reported to be more effective than the conventional Papanicolaou test in the detection of squamous intraepithelial lesions. OBJECTIVE: This retrospective analysis evaluated the validity of the findings on the thin-layer method using case material at a large independent laboratory and represented a comparison of performance of both methods over an identical period. METHODS: Data for conventional and ThinPrep tests were compared for 2 periods. Period 1 included 1,421,080 conventional and 56,835 ThinPrep specimens, and period 2 included 564,270 conventional and 109,784 ThinPrep specimens. Squamous intraepithelial lesions were used to determine detection of disease. These 2 sets of data were also analyzed to eliminate effects of any selection bias toward ThinPrep for high-risk patients. RESULTS: Use of ThinPrep showed a greater than 100% increase in the detection rate of squamous intraepithelial lesions (1.3%-3.4% in period 1 and 1.3%-2.9% in period 2), which was statistically significant after correcting for selection bias. We also found a significant decrease in the false-negative proportion (57% in period 1 and 35% in period 2). There was a marked improvement (233%) in the detection of high-grade squamous intraepithelial lesions in high-risk cases and a decrease in the atypical squamous cells of undetermined significance to squamous intraepithelial lesion ratio from 3.1 to 1.5 in period 2. CONCLUSION: ThinPrep is better than the conventional Papanicolaou test in detecting squamous intraepithelial lesions and is a superior screening test in detection of precancerous changes of the cervix.

False Negative Reactions↗
PubMed2003

[Effects of La on the growth of kidney bean seedling under Cd stress].

In this study, kidney bean (Phaseolus vulgaris) was used as experiment-material, and effects of lanthanum on growth and metabolism of kidney bean seedling under cadmium stress was studied by water culture. The results showed that kidney bean seedling was chronically harmed by 30 mumol.L-1 Cd2+, however, its height and main root were reduced about 31.1% and 39.2%, meanwhile, leaf area, fresh and dry weight of leaf, stem and root were decreased 48.0%, 42.7%, 29.6%, 61.3% and 49.4% respectively. With acute damage of 50 mumol.L-1 Cd2+, physiological and biochemical characteristics of seedling changed greatly, e.g., chlorophyll content and root activity were decreased about 23.5% and 28.7%, cell membrane permeability, the malonydialdehyde (MDA) content, activities of catalase (CAT) and peroxidase (POD) were increased 5.58%, 28.6%, 0.6% and 7.0% respectively. And with longer treatment time, the damage became more serious. When 10 mg.L-1 La was used to spray on kidney bean seedling under cadmium stress one time, growth and metabolism of seedling was obviously reconditioned and the damage of Cd pollution was reduced. It is proved, by the experiment, that La can improve chlorophyll content(30.0%) and reduce cell membrane permeability (0.87%) and content of MDA(9.5%), and keep the activities of CAT (0.1%) and POD(1.6%) of kidney bean seedling.

Cadmium↗