Search PubMed⌕ Search

Biomedical subjects

Hui Xu

Publications and source records attributed to Hui Xu.

At least 73 records · Page 4Linked to original sources
PubMed2005

Proteomic analysis of kidney in fluoride-treated rat.

The recent development of proteomic techniques has enabled investigators to directly examine the population of proteins present in biological systems. We first report here the proteomic changes of renal protein induced by fluoride. To investigate molecular mechanisms of renal injury induced by fluoride, proteins were isolated from rat kidney and profiled by two-dimensional gel electrophoresis (2DE). With the analysis of Image-Master 2D Elite software, 141 up-regulated and eight down-regulated protein spots in 2DE gels of fluoride-treated group were gained by comparison to the control group, 13 of which were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The identified proteins are mainly related with cell proliferation, metabolism and oxidative stress, and provide a valuable clue to explore the mechanism of renal fluorosis. This study also shows that the proteomic techniques were powerful in fluoride toxical field.

Animals↗
PubMed2005

Rapid, simultaneous determination of headspace oxygen and moisture in pharmaceutical packages using muGC.

The rapid, accurate determination of headspace oxygen and moisture in various pharmaceutical packages is important for both product packaging development and the implementation of new packaging technologies. Current headspace oxygen measurement techniques suffer from serious drawbacks in terms of potential sampling contamination, lengthy analysis times, and large required analysis volumes. In addition, relatively few techniques currently exist for the convenient determination of headspace moisture in packaging systems. Efforts herein focused on the development and application of a new method for the rapid and simultaneous determination of headspace oxygen and moisture in pharmaceutical packages using micro-gas chromatography (muGC). Studies showed that both headspace oxygen and moisture could be simultaneously quantified in <90 s on sample volumes of 50-100 microL by employing muGC with dual chromatographic analysis modules. Sampling issues common to manual syringe-based injections were also alleviated in the current studies by use of the built-in diaphragm pump sampling interface of the portable muGC system. The performance of the analytical approach was evaluated and shown to exhibit excellent linearity, accuracy, and precision for both analytes. High sensitivity for headspace oxygen was demonstrated, allowing for levels of oxygen as low as 0.03% to be accurately quantified. The subject method was applied to measure the headspace oxygen and moisture in pharmaceutical blister packaging and glass vials.

Chromatography, Gas↗
PubMed2005

Molecular visualization of conformation-triggered flow instability.

A new type of flow fingering instability was observed in monolayer-thick polymer films as they spread on a solid substrate. Tracing the movement of individual molecules by atomic force microscopy enabled us to follow the development of the flow instability on the molecular level and to understand the underlying physical mechanism. The fingering instability was observed to be triggered by conformational changes of brushlike macromolecules in response to the pressure gradient driving the flow.

Journal Article↗
PubMed2005

Transglutaminase activity is present in highly purified nonsynaptosomal mouse brain and liver mitochondria.

Several active transglutaminase (TGase) isoforms are known to be present in human and rodent tissues, at least three of which, namely, TGase 1, TGase 2 (tissue transglutaminase), and TGase 3, are present in the brain. TGase activity is known to be present in the cytosolic, nuclear, and extracellular compartments of the brain. Here, we show that highly purified mouse brain nonsynaptosomal mitochondria and mouse liver mitochondria and mitoplast fractions derived from these preparations possess TGase activity. Western blotting and experiments with TGase 2 knock-out (KO) mice ruled out the possibility that most of the mitochondrial/mitoplast TGase activity is due to TGase 2, the TGase isoform responsible for the majority of the activity ([14C]putrescine-binding assay) in whole brain and liver homogenates. The identity of the mitochondrial/mitoplast TGase(s) is not yet known. Possibly, the activity may be due to one of the other TGase isoforms or perhaps to a protein that does not belong to the classical TGase family. This activity may play a role in regulation of mitochondrial function both in normal physiology and in disease. Its nature and regulation deserve further study.

Animals↗
PubMed2005

Magnetically assisted DNA assays: high selectivity using conjugated polymers for amplified fluorescent transduction.

We report a strategy for conjugated polymer (CP)-based optical DNA detection with improved selectivity. The high sensitivity of CP-based biosensors arises from light harvesting by the CP and the related amplified fluorescent signal transduction. We demonstrate that the use of magnetic microparticles significantly improves the selectivity of this class of DNA sensors. Compared with previously reported DNA sensors with CP amplification, this novel sensing strategy displays excellent discrimination against non-cognate DNA in the presence of a protein mixture or even human serum. We also demonstrate that the magnetically assisted DNA sensor can conveniently identify even a single-nucleotide mismatch in the target sequence.

Base Pair Mismatch↗
PubMed2005

Reduction in the E2k subunit of the alpha-ketoglutarate dehydrogenase complex has effects independent of complex activity.

The activity of the alpha-ketoglutarate dehydrogenase complex (KGDHC) declines in brains of patients with several neurodegenerative diseases. KGDHC consists of multiple copies of E1k, E2k, and E3. E1k and E2k are unique to KGDHC and may have functions independent of the complex. The present study tested the consequences of different levels of diminished E2k mRNA on protein levels of the subunits, KGDHC activity, and physiological responses. Human embryonic kidney cells were stably transfected with an E2k sense or antisense expression vector. Sense control (E2k-mRNA-100) was compared with two clones in which the mRNA was reduced to 67% of control (E2k-mRNA-67) or to 30% of control (E2k-mRNA-30). The levels of the E2k protein in clones paralleled the reduction in mRNA, and E3 proteins were unaltered. Unexpectedly, the clone with the greatest reduction in E2k protein (E2k-mRNA-30) had a 40% increase in E1k protein. The activity of the complex was only 52% of normal in E2k-mRNA-67 clone, but was near normal (90%) in E2k-mRNA-30 clone. Subsequent experiments tested whether the physiological consequences of a reduction in E2k mRNA correlated more closely to E2k protein or to KGDHC activity. Growth rate, increased DCF-detectable reactive oxygen species, and cell death in response to added oxidant were proportional to E2k proteins, but not complex activity. These results were not predicted because subunits unique to KGDHC have never been manipulated in mammalian cells. These results suggest that in addition to its essential role in metabolism, the E2k component of KGDHC may have other novel roles.

Acyltransferases↗
PubMed2005

Study of microbial community structures in UASB sludge treating municipal wastewater by denaturing gradient gel electrophoresis of 16S rDNA.

The structures of microbial communities in lab-scale upflow anaerobic sludge blanket (UASB) reactors for treating municipal wastewater with different ratios of COD soluble/COD total were studied using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes. The microbial structure of the inoculum sludge obtained from a full-scale UASB reactor of treating potato processing wastewater was compared with the structures of sludges collected from three lab-scale UASB reactors after eight months feeding with raw municipal wastewater, with CEPS (chemically enhanced primary sedimentation) pretreated municipal wastewater, and with a synthetic municipal sewage, respectively. Computer-aided numerical analysis of the DGGE fingerprints showed that the bacterial community underwent major changes. The sludges for treating raw and CEPS pretreated wastewater had very similar bacterial and archaeal communities (82% and 96% similarity) but were different from that for treating the synthetic sewage. Hence, despite similar % COD in the particulate form in the synthetic and the real wastewater, the two wastewaters were selected for different microbial communities. Prominent DGGE bands of Bacteria and Archaea were purified and sequenced. The 16S rRNA gene sequences of the dominant archaeal bands found in the inoculum, and UASB sludge fed with raw sewage, CEPS pretreated wastewater, and synthetic sewage were closely associated with Methanosaeta concilii. In the UASB sludge fed with synthetic sewage, another dominant band associated with an uncultured archaeon 39-2 was found together with M. concilii.

Anaerobiosis↗
PubMed2005

Long-term outcome of augmentation of the maxillary sinus using deproteinised bone particles experimental study in rabbits.

We studied the long-term outcome of deproteinised bone particles for augmentation of the maxillary sinus in rabbits. Histologically, 64 weeks after implantation, most of the newly formed bone in the augmented spaces had been absorbed. Histomorphometric analysis showed a significant reduction in the area of bone and a significant increase in the area of bone marrow. There was no substantial change in the area of deproteinised bone particles. We conclude that deproteinised bone particles do not absorb with time and that the newly formed bone in the augmented space after implantation is not stable in the long-term.

Analysis of Variance↗
PubMed2005

Histomorphometric study of the stability of newly formed bone after elevation of the floor of the maxillary sinus.

We studied the remodelling process of newly formed bone and the distribution of osteoclasts in the augmented space after elevation of the floor of the maxillary sinus in rabbits. Histologically, 10 weeks after grafting, there was some newly formed lamellar bone embedded in fatty tissue. Histomorphometric analysis showed that the augmented height and augmented area decreased significantly from 2 to 6 weeks. The number of osteoclasts on newly formed bone, adjacent to the elevated sinus membrane, was significantly greater than in the augmented space at 2 and 4 weeks. We conclude that newly formed bone in the augmented space after grafting with blood clot is unstable during the early stage of bony regeneration.

Acid Phosphatase↗
PubMed2005

Mitochondrial function in fibroblasts with aging in culture and/or Alzheimer's disease.

Mitochondrial membrane potentials (MMP) reflect the functional state of the mitochondria within cells. Our recently published method provides a quantitative estimate of the MMP of populations of mitochondrial-like particles (MLP) within living cells at 37 degrees C using the combination of conventional fluorescence microscopy, 3D-deconvolution and exhaustive photon reassignment (EPR). Although the method does not provide an absolute measure of MMP, these relative MMP allow direct comparison between various mitochondria in cells at various ages in culture and in different cell lines from multiple patients. Fibroblasts lines from four Alzheimer's disease (AD) patients bearing the presenilin-1 (PS-1) mutation and four appropriate controls were evaluated at different ages in culture. The results showed a large variation in the relative MMP, cell size and sum of relative MMP of all MLP within each cell or within each cell line. Nevertheless, combining the values of relative MMP for the cell lines in each group revealed changes in distribution with age in culture. The relative MMP decreased while the cell sizes and sum of relative MMP within each cell increased with age in fibroblasts. Values did not differ between controls and the AD patients bearing PS-1 mutation at any age in cultures. This new, sensitive and quantitative estimate of relative MMP indicates that under non-stressed conditions relative MMP change with aging in culture, but relative MMP do not differ between controls and AD subjects.

Adult↗
PubMed2005

A direct comparison of two nonviral gene therapy vectors for somatic integration: in vivo evaluation of the bacteriophage integrase phiC31 and the Sleeping Beauty transposase.

In this study we performed a head-to-head comparison of the integrase phiC31 derived from a Streptomyces phage and the Sleeping Beauty (SB) transposase, a member of the TC1/mariner superfamily of transposable elements. Mouse liver was cotransfused with a vector containing our most robust human coagulation factor IX expression cassette and the appropriate recombinase recognition site and either a phiC31- or a SB transposase-expressing vector. To analyze transgene persistence and to prove somatic integration in vivo we induced cell cycling of mouse hepatocytes and found that the transgene expression levels dropped by only 16 to 21% and 56 to 66% in mice that received phiC31 and SB, respectively. Notably, no difference in the toxicity profile was detected in mice treated with either recombinase. Moreover we observed that with the integrase-mediated gene transfer, transgene expression levels were dependent on the remaining noncoding vector sequences, which also integrate into the host genome. Further analyses of a hot spot of integration after phiC31-mediated integration revealed small chromosomal deletions at the target site and that the recombination process was not dependent on the orientation in which the phiC31 recognition site attached to the pseudo-recognition sites in the host genome. Coupled together with ongoing improvements in both systems this study suggests that both nonviral vector systems will have important roles in achieving stable gene transfer in vivo.

Animals↗
PubMed2005

Peptide mediated formation of hierarchically organized solution and solid state polymer nanostructures.

Biologically-inspired peptide sequences have been explored as auxiliaries to mediate self-assembly of synthetic macromolecules into hierarchically organized solution and solid state nanostructures. Peptide sequences inspired by the coiled coil motif and "switch" peptides, which can adopt both amphiphilic alpha-helical and beta-strand conformations, were conjugated to poly(ethylene glycol) (PEG). The solution and solid state self-assembly of these materials was investigated using a variety of spectroscopic, scattering and microscopic techniques. These experiments revealed that the folding and organization properties of the peptide sequences are retained upon conjugation of PEG and that they provide the driving force for the formation of the different nanoscale structures which were observed. The possibility of using defined peptide sequences to direct structure formation of synthetic polymers together with the potential of peptide sequences to induce a specific biological response offers interesting prospects for the development of novel self-assembled and biologically active materials.

Amino Acid Sequence↗
PubMed2005

Targeting vaccinia to solid tumors with local hyperthermia.

We have previously demonstrated that mutant vaccinia viruses target tumors in vivo after systemic delivery, and they have potential as vectors for tumor-directed gene therapy. We hypothesized that hyperthermia may augment vaccinia delivery to tumors after systemic injection, as hyperthermia increases the permeability of the endothelial vasculature to nanoparticles. In our in vitro experiments, we have shown that hyperthermia does not alter tumor cells' susceptibility to the intrinsic cytopathogenicity of the vaccinia virus compared with normothermic controls. Hyperthermia also does not change the viral infectivity or the level of viral marker gene expression when compared with normothermia. In an in vitro model of endothelial cell monolayer permeability, we have demonstrated that hyperthermia increases the permeability of the monolayer to vaccinia virus and that this phenomenon is completely reversible. In vivo we have demonstrated that the tumors that were treated with systemic vaccinia under conditions of hyperthermia (41.5 degrees C for 30 min) had significantly higher levels of vaccinia marker gene activity (>100-fold) than those treated under normothermic conditions (p < 0.05) and that this effect was specific to tumor. We also demonstrated that mice with 1 cm subcutaneous tumors treated with a systemically delivered, conditionally replicating vaccinia under conditions of hyperthermia had complete tumor regression in 50% and significantly improved antitumor response, compared with normothermic viral-treated controls (mean tumor volume of 110 mm(3) vs 3169 mm(3), 13 days after treatment) and compared with hyperthermic, nonvirally treated control animals (p < 0.0001). Regional hyperthermia improves vaccinia targeting to tumors, and thereby enhances the antitumor response.

Animals↗
PubMed2005

Inhibition of the alpha-ketoglutarate dehydrogenase complex by the myeloperoxidase products, hypochlorous acid and mono-N-chloramine.

Abstract alpha-Ketoglutarate dehydrogenase (KGDHC) complex activity is diminished in a number of neurodegenerative disorders and its diminution in Alzheimer Disease (AD) is thought to contribute to the major loss of cerebral energy metabolism that accompanies this disease. The loss of KGDHC activity appears to be predominantly due to post-translation modifications. Thiamine deficiency also results in decreased KGDHC activity and a selective neuronal loss. Recently, myeloperoxidase has been identified in the activated microglia of brains from AD patients and thiamine-deficient animals. Myeloperoxidase produces a powerful oxidant, hypochlorous acid that reacts with amines to form chloramines. The aim of this study was to investigate the ability of hypochlorous acid and chloramines to inhibit the activity of KGDHC activity as a first step towards investigating the role of myeloperoxidase in AD. Hypochlorous acid and mono-N-chloramine both inhibited purified and cellular KGDHC and the order of inhibition of the purified complex was hypochlorous acid (1x) > mono-N-chloramine (approximately 50x) > hydrogen peroxide (approximately 1,500). The inhibition of cellular KGDHC occurred with no significant loss of cellular viability at all exposure times that were examined. Thus, hypochlorous acid and chloramines have the potential to inactivate a major target in neurodegeneration.

Animals↗
PubMed2005

Blood-filled spaces with and without deproteinized bone grafts in guided bone regeneration. A histomorphometric study of the rabbit skull using non-resorbable membrane.

This experimental study evaluated the effects of deproteinized bone grafts on guided bone regeneration (GBR). A groove was made in the bone marrow of the external cortical plate of the skull. A dome of non-resorbable membrane was placed on the groove and secured with titanium pins. The secluded graft space was filled with autogenous blood clots (control group) and deproteinized bone particles (experimental group). The rabbits were sacrificed 2, 4, 8 and 12 weeks after the operation. Decalcified and paraffin-embedded, transverse 3-mum-thick sections were made and stained with hematoxylin and eosin. The proportions of newly formed bone and newly formed bone-graft particle contact surfaces were histomorphometrically measured in the basal, central, and peripheral areas from the cortical plate to the top of the dome. In the control group, the basal area showed a significant increase at 4 weeks (P<0.01) and a significant decrease at 8 weeks (P<0.01). The central and peripheral areas showed gradual increases in the proportion of newly formed bone. The experimental group showed significant increase at 4 weeks in the basal area and at 8 weeks in central and peripheral area (P<0.01). There were significant differences between both groups in basal and central area (P<0.01). The proportion of newly formed bone-graft particle contact length showed significant increases at 4 weeks (P<0.01) and no significant decreases at 8 and 12 weeks in three areas. The present study showed that deproteinized bone grafts maintain newly formed bone in extensive areas for a prolonged period during GBR.

Animals↗
PubMed2005

Warfarin or low-molecular-weight heparin therapy does not prolong pig-to-primate cardiac xenograft function.

Microvascular thrombosis is a prominent feature in cardiac delayed xenograft rejection (DXR). We investigated the impact of warfarin or low-molecular-weight heparin (LMWH) anti-coagulation on xenograft function using a heterotopic pig-to-primate model. Donor hearts were from CD46 transgenic pigs and baboon immunosuppression included tacrolimus, sirolimus, anti-CD20 and TPC, an alpha-galactosyl-polyethylene glycol conjugate. Three groups of animals were studied. Group 1 (n = 9) was treated with warfarin, Group 2 (n = 13) with LMWH and Group 3, received no anti-coagulant drugs. The median duration of xenograft function was 20 days (range 3-62 days), 18 days (range 5-109 days) and 15 days (range 4-53 days) in Groups 1 to 3 respectively. Anti-coagulation achieved the targeted international normalized prothrombin ratio (INR) and anti-factor Xa levels consistent with effective in vivo therapy yet, no significant impact on median xenograft function was observed. At rejection, a similar histology of thrombosis and ischemia was apparent in each group and the levels of fibrin deposition and platelet thrombi in rejected tissue was the same. Anti-coagulation with warfarin or LMWH did not have a significant impact on the onset of DXR and microvascular thrombosis. However, a role for specific anti-coagulant strategies to achieve long-term xenograft function cannot be excluded.

Animals↗
PubMed2005

Proteomic characterization of skin and epidermis in response to environmental agents.

The skin and its outer epidermis layer in particular, prevent access of various environmental agents including potential allergens, irritants, carcinogens, ultraviolet radiation and microbes. Cells in the epidermis make a significant contribution to innate as well as adaptive immune reactions in skin. The skin immunity thus provides a biologic defense in response to hazardous environmental agents. Although proteomics has been utilized to establish skin proteomes and investigate skin responses to some environmental agents, it has not been extensively used to address the complexity of skin responses to various environments. This review summarizes cutaneous genes and proteins that have been characterized as related to skin exposure to environmental agents. In parallel, this review emphasizes functional proteomics and systems biology, which are believed to be an important future direction toward characterizing the skin proteome-environmental interaction and developing successful therapeutic strategies for skin diseases caused by environmental insults.

Animals↗