Biomedical subjects

Hao Wu

Publications and source records attributed to Hao Wu.

At least 127 records · Page 7Linked to original sources

PubMed2003

TRAF6, a molecular bridge spanning adaptive immunity, innate immunity and osteoimmunology.

Tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6) is a crucial signaling molecule regulating a diverse array of physiological processes, including adaptive immunity, innate immunity, bone metabolism and the development of several tissues including lymph nodes, mammary glands, skin and the central nervous system. It is a member of a group of six closely related TRAF proteins, which serve as adapter molecules, coupling the TNF receptor (TNFR) superfamily to intracellular signaling events. Among the TRAF proteins, TRAF6 is unique in that, in addition to mediating TNFR family signaling, it is also essential for signaling downstream of an unrelated family of receptors, the interleukin-1 (IL-1) receptor/Toll-like receptor (IL-1R/TLR) superfamily. Gene targeting experiments have identified several indispensable physiological functions of TRAF6, and structural and biochemical studies have revealed the potential mechanisms of its action. By virtue of its many signaling roles, TRAF6 represents an important target in the regulation of many disease processes, including immunity, inflammation and osteoporosis.

Animals↗

PubMed2003

Chemical and pharmacological investigations of Epimedium species: a survey.

More than 130 different compounds have been identified from over 16 species of the Epimedium genus of the Berberidaceae family. Eight of these species have been used in the Traditional Chinese Medicines (TCM) over centuries to treate a wide range of diseases. From in vitro and in vivo experimental data, and preliminary structure-activity relationship (SAR) analysis of the androgenic/anti-estrogenic and anti-oxidant activities of the icariin series of flavonoids and glycosides, the results appear to be consistent with those of known anti-estrogenic flavonoids, such as luteolin. Further QSAR analysis of the different active ingredients is now in progress and will be reported elsewhere. Our survey suggests the possibility of multiple targets and multiple mechanisms of action by Epimedium preparations and their purified compounds. These may serve as leads for further new drug development.

Animals↗

PubMed2003

Overexpression of extracellular matrix metalloproteinase inducer in multidrug resistant cancer cells.

Multidrug resistant (MDR) cancer cells overexpressing P-glycoprotein (P-gp) display variations in invasive and metastatic behavior. We previously reported that these properties of MDR cancer cell lines overexpressing P-gp could be altered by chemotherapeutic drugs or MDR modulators (R. S. Kerbel et al., Cancer Surv., 7: 597-629, 1988). To attempt to clarify the mechanism(s) underlying these observations, we studied the expression of extracellular matrix metalloproteinase inducer (EMMPRIN), a glycoprotein enriched on the surface of tumor cells that can stimulate the production of matrix metalloproteinases (MMPs), in sensitive and MDR cancer cells. Using immunofluorescence staining and fluorescence-activated cell sorting analysis, we found that EMMPRIN expression was increased in MDR carcinoma cell lines, MCF-7/AdrR, KBV-1, and A2780Dx5, as compared to their parental counterparts. The MDR cell lines produced more matrix metalloproteinase-1 (MMP-1), matrix metalloproteinase-2 (MMP-2), and matrix metalloproteinase-9 (MMP-9), as determined by zymography, Western blot, and reverse transcription-PCR. Treatment of MDR cells with an anti-EMMPRIN antibody inhibited the activity of MMP-1, MMP-2, and MMP-9. In MDR cell line MCF-7/AdrR, an increased in vitro invasive ability was observed as compared with the sensitive line MCF-7, and EMMPRIN antibody could inhibit the in vitro invasion in drug-resistant cells. In addition, the expression and activity of MMP-1, MMP-2, and MMP-9 in MDR cells were decreased by treatment with U-0126, an inhibitor of mitogen-activated protein kinase/extracellular signal regulated kinase (MAPK/Erk). Our results suggest that during the development of MDR, the expression of EMMPRIN is responsible for the increased activity of MMP in MDR cell lines.

Antigens, CD↗

PubMed2003

[Surgical management of Mondini dysplasia with cerebrospinal fluid leakage].

OBJECTIVE: To evaluate the clinical manifestation and surgical technique of Mondini dysplasia with cerebrospinal fluid (CSF) leakage. METHOD: Three Mondini dysplasia with spontaneous cerebrospinal fluid leakage were treated by the authors. A transcanal tympanotomy were used to pack the vestibular cavity with muscle. RESULT: Three children were first manifested with recurrent meningitis and spontaneous cerebrospinal fluid rhinorrhea. Further examinations found that the leakages were otogenic. One side or both sides Mondini dysplasia were confirmed by CT scanning of temporal bones. The leakages were all stopped by the primary surgical closure. CONCLUSION: Mondini dysplasia should be considered in children with spantaneous cerebrospinal fluid otorhinorrhea. A temporal bone CT scan can confirmed the diagnosis. A transtympanic closure is very effective in the management.

Cerebrospinal Fluid Otorrhea↗

PubMed2003

[Diagnosis and treatment of spinal dural arteriovenous fistulas: 110 cases report].

OBJECTIVE: To discuss the diagnosis, treatment and prognosis of spinal dural arteriovenous fistulas (SDAVF). METHODS: The clinical and following-up date from 110 patients with SDAVF diagnosed by spinal MRI and spinal angiography were analyzed retrospectively. RESULTS: Draining vein between fistula and spinal cord was interrupted by laminectomy approach as first choice in 61 patients, by hemi-laminectomy approach in 37, and by endovascular embolization in 12, and re-operation due to recurrence after embolization in 3. Anticoagulation, hydration and early rehabilitation were used postoperatively. Complete disappearance of SDAVF was confirmed in all 106 patients who received postoperative spinal angiography. The para-medullary tortuous flow voids fully disappeared in 74 patients and partly disappeared in 15 on postoperative T(2)-weighted MRI. Follow up of 98 patients showed complete recovery in 54 patients, improvement in 34, and no change in 10. Three of the 10 patients were reoperated on because of recurrence 1 to 5 years after embolization. CONCLUSIONS: SDAVF can produce good outcome after early diagnosis and treatment. Interruption of the draining vein between fistula and spinal cord by hemi-laminectomy approach is the first choice for the treatment of SDAVF.

Adult↗

PubMed2003

Early X-ray and CT appearances of severe acute respiratory syndrome: an analysis of 28 cases.

OBJECTIVE: To study the early X-ray and CT findings of patients with severe acute respiratory syndrome (SARS). METHODS: Chest radiography and CT were performed in 28 patients with SARS within one to three days after onset of the disease. CT examinations included conventional spiral CT and high-resolution CT (HRCT). The radiographic and CT findings of these patients were analyzed retrospectively. RESULTS: Abnormal CT findings were noted in all the patients, but abnormal chest radiographic findings in 17 cases (60.7%, 17/28). CT showed single small focal patchy opacities in 23 patients (82.1%, 23/28), including oval ground-glass opacities in 20 patients, lobular distribution ground-glass opacities in 2 and small patchy consolidation in one. Multi-focal ground-glass opacities were found in 2 patients and extensive opacities in three. In the 28 patients, a total of 31 lesions were found in the upper (7, 22.6%), middle (3, 9.7%), and lower lobes (21, 67.7%). The diameter of the lesions ranged from 20 to 35 mm. CONCLUSION: The dominant feature of early SARS patients is focal patchy opacity in the lung, and oval small ground-glass opacities are the common morphological findings on CT.

Adult↗

PubMed2003

[Prevention and therapy of cerebrospinal fluid leakage after translabyrinthine acoustic neuroma removal].

OBJECTIVE: To evaluate the modified wound closure technique and other methods for preventing and treating the cerebrospinal fluid (CSF) leakage after removal of acoustic neuroma by translabyrinthine approach. METHODS: In a series of 85 cases of acoustic neuroma surgery, two kinds of technique of wound closure, the traditional (as first group) and the modified (as second group), have been subsequently used to prevent CSF leakage. The incidences of CSF leak were analyzed respectively. Conservative and surgical treatments were applied to treatment the CSF leak. RESULTS: In the first group, the CSF leak was 19.5% (8/41), and that of second group was 2.3% (1/44). There was significant difference between them (P = 0.013). The CSF leak mainly occurred in large acoustic neuromas surgery with traditional wound closure technique. Among 9 cases of CSF leaks, 3 were controlled by conservative method, 5 by one single revision surgery and one by two revisions. CONCLUSIONS: The revision technique of wound closure could significantly reduce the incidence of CSF leakage after acoustic neuroma removal by translabyrinthine approach. The revision surgery is an effective method for stopping the CSF leak.

Adult↗

PubMed2003

[Effect of somatostatin on modulation of IL-10 and TGF-beta 1 during acute pancreatitis].

OBJECTIVE: To observe the effect of somatostatin on modulation of IL-10 and TGF-beta 1 in acute pancreatitis and investigate the mechanism. METHODS: SD male rats were divided into 3 groups: Group 1, the normal rats as control (n = 6); Group 2, the rats with acute pancreatitis induced by ductual injection with 5% sodium cholate sulfur at the volume of 0.6 ml/kg without any other treatment (n = 8); Group 3, after pancreatitis were induced, the rats were injected hypodermically with somatostatin 3 micrograms/(kg.hr)(n = 6). The animals were killed at 2, 6 and 24 hours after operation (each period n = 7). The blood samples were taken for measurement of IL-10 and TGF-beta 1 (by ELISA). The weight of pancreatic tissue and amylopsin was also observed. RESULTS: Both IL-10 and TGF-beta 1 in blood of acute pancreatitis increased significantly (P < 0.05). After the injection of somatostatin, IL-10 and TGF-beta 1 were found remarkably decreased at 24 hours postoperation (P < 0.05). No changes of the weight of pancreatic tissue and amylopsin were observed after the injection of somatostatin. CONCLUSION: Somatostatin can depress the increase of inflammatory-associated cytokines (IL-10 and TGF-beta 1) that increased remarkably in acute pancreatitis, which is one of the most important reasons why somatostatin cannot relieve pancreatitis.

Acute Disease↗

PubMed2003

[Distinctive compound in Rhizome of Pinellia ternata].

OBJECTIVE: To look for and determine the distinctive compound in Pinellia ternata. METHOD: With TLC, HPLC, the distinctive compound was found and obtained by using the method of HPLC preparation. Its structure was elucidated by spectral analysis and physico-chemical properties. RESULT: The compound was identified as inosine. CONCLUSION: Inosine is the distinctive compound in Rhizome of P. ternata, and it was isolated from Banxia for the first time.

Chromatography, High Pressure Liquid↗

PubMed2002

CD4 dimers constitute the functional component required for T cell activation.

The CD4 molecule plays a key role in the development and activation of helper T cells. Dimerization and oligomerization is often a necessary step in the function of several cell surface receptors. Herein, we provide direct biochemical evidence confirming the presence of CD4 as dimers in transfected cells from hemopoetic and fibroblastic origin as well as in primary T cells. Such dimers are also observed with murine CD4 confirming selective pressure during evolution to maintain such a structure. Using a series of point mutations, we have precisely mapped the dimerization site at residues K318 and Q344 within the fourth extracellular domain of CD4. These residues are highly conserved and their mutation results in interference with dimer formation. More importantly, we demonstrate that dimer formation is essential for the coligand and coreceptor functions of CD4 in T cell activation. These data strongly suggest that CD4 dimerization is necessary for helper T cell function.

Amino Acid Sequence↗

PubMed2002

Mutational analyses of the p35-caspase interaction. A bowstring kinetic model of caspase inhibition by p35.

Apoptosis is a highly regulated multistep process for programmed cellular destruction. It is centered on the activation of a group of intracellular cysteine proteases known as caspases. The baculoviral p35 protein effectively blocks apoptosis through its broad spectrum caspase inhibition. It harbors a caspase recognition sequence within a highly protruding reactive site loop (RSL), which gets cleaved by a target caspase before the formation of a tight complex. The crystal structure of the post-cleavage complex between p35 and caspase-8 shows that p35 forms a thioester bond with the active site cysteine of the caspase. The covalent bond is prevented from hydrolysis by the N terminus of p35, which repositions into the active site of the caspase to eliminate solvent accessibility of the catalytic residues. Here, we report mutational analyses of the pre-cleavage and post-cleavage p35/caspase interactions using surface plasmon resonance biosensor measurements, pull-down assays and kinetic inhibition experiments. The experiments identify important structural elements for caspase inhibition by p35, including the strict requirement for a Cys at the N terminus of p35 and the rigidity of the RSL. A bowstring kinetic model for p35 function is derived in which the tension generated in the bowstring system during the pre-cleavage interaction is crucial for the fast post-cleavage conformational changes required for inhibition.

Apoptosis↗

PubMed2002

Characterization of the interactions between the small GTPase RhoA and its guanine nucleotide exchange factors.

A novel spectrophotometric method to study the kinetics of the guanine nucleotide exchange factors-catalyzed reactions is presented. The method incorporates two coupling enzyme systems: (a). GTPase-activating protein which stimulates the intrinsic GTP hydrolysis reaction of small GTPases and (b). purine nucleotide phosphorylase and its chromophoric substrate, 7-methyl-6-thioguanosine, for quantitation of the resultant inorganic phosphate. The continuous coupled enzyme system was used for characterization of the interactions between the small GTPase RhoA and its guanine nucleotide exchange factors, Lbc and Dbl. Kinetic parameters obtained here show that there is no significant difference in kinetic mechanism of these GEFs in interaction with RhoA. The Michaelis-Menten constants were determined to be around 1micro M, and the rate constants k(cat) were around 0.1s(-1).

A Kinase Anchor Proteins↗

PubMed2002

The use of construct variation and diffraction data analysis in the crystallization of the TRAF domain of human tumor necrosis factor receptor associated factor 6.

Obtaining soluble proteins and diffraction-quality crystals often represents the bottleneck in macromolecular crystallography. Here, it is shown that construct variation can be an efficient strategy in expressing soluble proteins from bacteria and that clues from poor crystals may be used to improve crystal packing and to optimize crystal quality.

Binding Sites↗

PubMed2002

Distinct molecular mechanism for initiating TRAF6 signalling.

Tumour-necrosis factor (TNF) receptor-associated factor 6 (TRAF6) is the only TRAF family member that participates in signal transduction of both the TNF receptor (TNFR) superfamily and the interleukin-1 receptor (IL-1R)/Toll-like receptor (TLR) superfamily; it is important for adaptive immunity, innate immunity and bone homeostasis. Here we report crystal structures of TRAF6, alone and in complex with TRAF6-binding peptides from CD40 and TRANCE-R (also known as RANK), members of the TNFR superfamily, to gain insight into the mechanism by which TRAF6 mediates several signalling cascades. A 40 degrees difference in the directions of the bound peptides in TRAF6 and TRAF2 shows that there are marked structural differences between receptor recognition by TRAF6 and other TRAFs. The structural determinant of the petide TRAF6 interaction reveals a Pro-X-Glu-X-X-(aromatic/acidic residue) TRAF6-binding motif, which is present not only in CD40 and TRANCE-R but also in the three IRAK adapter kinases for IL-1R/TLR signalling. Cell-permeable peptides with the TRAF6-binding motif inhibit TRAF6 signalling, which indicates their potential as therapeutic modulators. Our studies identify a universal mechanism by which TRAF6 regulates several signalling cascades in adaptive immunity, innate immunity and bone homeostasis.

Amino Acid Motifs↗

PubMed2002

All TRAFs are not created equal: common and distinct molecular mechanisms of TRAF-mediated signal transduction.

The tumor necrosis factor (TNF) receptor associated factors (TRAFs) have emerged as the major signal transducers for the TNF receptor superfamily and the interleukin-1 receptor/Toll-like receptor (IL-1R/TLR) superfamily. TRAFs collectively play important functions in both adaptive and innate immunity. Recent functional and structural studies have revealed the individuality of each of the mammalian TRAFs and advanced our understanding of the underlying molecular mechanisms. Here, we examine this functional divergence among TRAFs from a perspective of both upstream and downstream TRAF signal transduction pathways and of signaling-dependent regulation of TRAF trafficking. We raise additional questions and propose hypotheses regarding the molecular basis of TRAF signaling specificity.

Amino Acid Sequence↗

PubMed2002

Development of new transformation-competent artificial chromosome vectors and rice genomic libraries for efficient gene cloning.

The transformation-competent artificial chromosome vector (TAC) system has been shown to be very useful for efficient gene isolation in Arabidopsis thaliana (Proc. Natl. Acad. Sci. USA 96 (1998) 6535). To adapt the vector system for gene isolation in crops, two new TAC vectors and rice genomic libraries were developed. The new vectors pYLTAC17 and pYLTAC27 use the Bar gene and Hpt gene driven by the rice Act1 promoter as the plant selectable markers, respectively, and are suitable for transformation of rice and other grasses. Two representative genomic libraries (I and II) of an Indica rice variety Minghui63, a fertility restorer line for hybrid rice, were constructed with pYLTAC17 using different size classes of partially digested DNA fragments. Library I and library II consisted of 34,560 and 1.2 x 10(5) clones, with average insert sizes of approximately 77 and 39 kb, respectively. The genome coverage of the libraries I and II was estimated to be about 5 and 11 haploid genome equivalents, respectively. Clones of the library I were stored individually in ninety 384-well plates, and those of the library II were collected as bulked pools each containing 30-50 clones and stored in eight 384-well plates. A number of probes were used to hybridize high-density colony filters of the library I prepared by an improved replicating method and each detected 2-9 positive clones. A method for rapid screening of the library II by pooled colony hybridization was developed. A TAC clone having an 80 kb rice DNA insert was successfully transferred into rice genome via Agrobacterium-mediated transformation. The new vectors and the genomic libraries should be useful for gene cloning and genetic engineering in rice and other crops.

Base Sequence↗

PubMed2002

DNA binding is required for the apoptogenic action of apoptosis inducing factor.

The execution of apoptosis or programmed cell death comprises both caspase-dependent and caspase-independent processes. Apoptosis inducing factor (AIF) was identified as a major player in caspase-independent cell death. It induces chromatin condensation and initial DNA cleavage via an unknown molecular mechanism. Here we report the crystal structure of human AIF at 1.8 A resolution. The structure reveals the presence of a strong positive electrostatic potential at the AIF surface, although the calculated isoelectric point for the entire protein is neutral. We show that recombinant AIF interacts with DNA in a sequence-independent manner. In addition, in cells treated with an apoptotic stimulus, endogenous AIF becomes co-localized with DNA at an early stage of nuclear morphological changes. Structure-based mutagenesis shows that DNA-binding defective mutants of AIF fail to induce cell death while retaining nuclear translocation. The potential DNA-binding site identified from mutagenesis also coincides with computational docking of a DNA duplex. These observations suggest that AIF-induced nuclear apoptosis requires a direct interaction with DNA.

Animals↗

PubMed2002

Role of angiotensin II and angiotensin II receptors in vascular smooth muscle cell migration in vitro.

OBJECTIVE: To determine the biotic effects of angiotensin II (Ang II) on the migration of rat smooth muscle cells (VSMCs) and investigate the mechanisms involved in the development of vascular injury. METHODS: VSMCs isolated from aortic media of Wistar rats and cultured by the modified explant method were adopted. In the presence and absence of Ang II, the expression of Ang II receptor (ATR) and reorganization of the actin cytoskeleton and focal adhesion of VSMCs were studied by an immunocytochemistry technique and fluorocytochemistry technique. Migration assays were performed with a modified Boyden's chamber. The effects of AT(1)R antagonist (CV-11974), AT(2)R antagonist (PD123319) on the aforementioned target were studied. RESULTS: VSMCs migration was stimulated by adding Ang II. The dynamic reorganization of actin cytoskeleton and focal adhesions may be an important mechanism by which Ang II facilitates VSMCs motility. The expression of AT(1)R in VSMCs could be upregulated initially after treatment with Ang II, then decreased gradually. The expression of AT(1)R was downregulated by AT(1)R antagonists. The effect of Ang II on VSMCs migration was mediated by AT(1)R, while AT(2)R had no significant effect. CONCLUSIONS: The dynamic reorganization of focal adhesions and the actin cytoskeleton is required for Ang II-induced VSMCs migration. This effect is mediated by AT(1)R.

Actins↗