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Hao Xu

Publications and source records attributed to Hao Xu.

At least 73 records · Page 4Linked to original sources
PubMed2004

A study of the cardioprotective effect of breviscapine during hypoxia of cardiomyocytes.

Breviscapine is a flavonoid extracted from Erigeron breviscapus. Hand.-Mazz, and it has been reported that breviscapine can activate K+ channels and block Ca2+ channels. In this paper, we studied the cardioprotective effects of breviscapine on electrocardiogram (ECG) changes (ST-segment elevation), infarction size in dog heart subjected to myocardial infarction caused by left coronary artery ligation and lactate dehydrogenase (LDH) leakage, changes of intracellular free Ca2+ levels, apoptosis and necrosis in cultured neonatal rat cardiomyocytes subjected to hypoxia. Additionally, the effect of breviscapine on myocardial oxygen consumption was detected in dog myocardium in vitro. The results showed that breviscapine treatment (1 mg/kg, 2 mg/kg and 4 mg/kg) significantly reduced ST-segment elevation and infarction size in hearts subjected to myocardial infarction, that breviscapine treatment (14.29 microg/mL, 28.57 microg/mL and 57.14 microg/mL) significantly decreased oxygen consumption in myocardium, and that breviscapine treatment (5 microg/mL, 10 microg/mL and 20 microg/mL) significantly reduced LDH leakage, intracellular free Ca2+ levels, apoptosis and necrosis in cardiomyocytes subjected to hypoxia. In conclusion, the present study indicates that breviscapine is in favor of myocardial protection.

Animals↗
PubMed2004

Novel substitutions in the sigma54-dependent activator DctD that increase dependence on upstream activation sequences or uncouple ATP hydrolysis from transcriptional activation.

Sinorhizobium meliloti DctD is an activator of sigma(54)-RNA polymerase holoenzyme and member of the AAA+ superfamily of ATPases. DctD uses energy released from ATP hydrolysis to stimulate the isomerization of a closed promoter complex to an open complex. DctD binds to upstream activation sequences (UAS) and contacts the closed complex through DNA looping to activate transcription, but the UAS is not essential for activation if DctD is expressed at higher than normal levels. Introduction of specific substitutions within or near the conserved ESELFG motif in the C3 region of a truncated, constitutively active form of DctD produced several mutant forms of the protein that had increased dependence on the UAS for activation. Removing the DNA-binding domain from one UAS-dependent mutant and from one activation-deficient mutant significantly increased transcriptional activation, indicating that the DNA-binding domain interfered with the activities of these mutant proteins. A UAS-dependent mutant with a P315L substitution in the C6 region was identified from a genetic screen. Alanine scanning mutagenesis of conserved amino acid residues around Pro-315 produced two additional UAS-dependent mutants as well as several mutants that failed to activate transcription but retained ATPase activity. In contrast to the two mutant proteins with substitutions in the C3 region, removal of the DNA-binding domain from the mutant proteins with substitutions in the C6 region did not stimulate their activity. The residues in the C6 region that were altered are in a probable hinge region between the alpha/beta and alpha-helical subdomains of the AAA+ domain. The alpha-helical subdomain contains the sensor II helix that has been implicated in other AAA+ proteins as sensing changes in the nucleotide during the hydrolysis cycle. Substitutions in the hinge region may have abolished nucleotide sensing by interfering with subdomain interactions, altering the relative orientation of the sensor II helix or interfering with oligomerization of the protein.

Adenosine Triphosphatases↗
PubMed2004

Purification and characterization of the AAA+ domain of Sinorhizobium meliloti DctD, a sigma54-dependent transcriptional activator.

Activators of sigma54-RNA polymerase holoenzyme couple ATP hydrolysis to formation of an open complex between the promoter and RNA polymerase. These activators are modular, consisting of an N-terminal regulatory domain, a C-terminal DNA-binding domain, and a central activation domain belonging to the AAA+ superfamily of ATPases. The AAA+ domain of Sinorhizobium meliloti C4-dicarboxylic acid transport protein D (DctD) is sufficient to activate transcription. Deletion analysis of the 3' end of dctD identified the minimal functional C-terminal boundary of the AAA+ domain of DctD as being located between Gly-381 and Ala-384. Histidine-tagged versions of the DctD AAA+ domain were purified and characterized. The DctD AAA+ domain was significantly more soluble than DctD(Delta(1-142)), a truncated DctD protein consisting of the AAA+ and DNA-binding domains. In addition, the DctD AAA+ domain was more homogeneous than DctD(Delta(1-142)) when analyzed by native gel electrophoresis, migrating predominantly as a single high-molecular-weight species, while DctD(Delta(1-142)) displayed multiple species. The DctD AAA+ domain, but not DctD(Delta(1-142)), formed a stable complex with sigma54 in the presence of the ATP transition state analogue ADP-aluminum fluoride. The DctD AAA+ domain activated transcription in vitro, but many of the transcripts appeared to terminate prematurely, suggesting that the DctD AAA+ domain interfered with transcription elongation. Thus, the DNA-binding domain of DctD appears to have roles in controlling the oligomerization of the AAA+ domain and modulating interactions with sigma54 in addition to its role in recognition of upstream activation sequences.

Bacterial Proteins↗
PubMed2004

[Suppression of neutrophil immune function in rabbit models of hemorrhagic shock complicated by intra-abdominal hypertension].

OBJECTIVE: To investigate the effects of hemorrhagic shock and intra-abdominal hypertension (IAH) on inflammatory responses of peripheral circulating neutrophils such as intracellular cytokine production, phagocytic capacity and expression of nuclear factor (NF)- kappaB. METHODS: Twenty-four rabbits were divided equally into 4 groups including a hemorrhagic shock (HS) group complicated by abdominal compartment syndrome (ACS) (Group A), a HS group (Group B), a ACS group (Group C) and a normal control group (Group D). Intracellular interleukin (IL)-8 production in the peripheral neutrophils were measured in the rabbits by flow cytometry, phagocytic function of the neutrophils evaluated by a chemiluminescence method and the NF-kappaB expression detected by immunocytochemistry before, immediately and 4 h after the traumatization. RESULTS: Four hours after the trauma, decreased intracellular IL-8 production and impaired phagocytic function of the peripheral neutrophils were observed in Group A along with suppressed NF-kappaB expression. But in Group B and Group C, the intracellular IL-8 production, phagocytic function and expression of NF-kappaB returned to the normal levels 4 hours after the trauma following the early-stage changes. In Group D, no significant changes occurred during the observation. CONCLUSIONS: Responsiveness and function of the neutrophils to the stimuli by endotoxin are suppressed by the sequential second-hit of IAH after hemorrhagic shock, which may contribute to the occurrence of sepsis in ACS.

Abdomen↗
PubMed2004

[Effect of xiongshao capsule on vascular remodeling in rabbit with experimental atherosclerosis].

OBJECTIVE: To study the effect of Xiongshao Capsule (XSC) on vascular remodeling in experimental atherosclerotic (AS) rabbits, and to explore the possible mechanisms. METHODS: Rabbit's fractional AS model was established by denuding and injuring the abdominal artery with 4F.Fogarty catheter, and followed with high cholesterol feeding. The animals were randomly divided into 8 groups, namely, the modeled group of 3 days, 2 weeks and 6 weeks after balloon injury (A, B and C); the single endothelium injury group (D), the probucol treating group (E), the low-dose and high-dose XSC treating group (F and G) and the normal control group (N). Except the rabbits in Group N and D, the other groups were all fed with high fat forage. Histopathological examination of abdominal aorta with the most obvious lesion was performed, and the changes of related vascular remodeling indexes after arterial injury were observed using computerized image analyzing system; the correlation analysis between progress of intimal proliferation and vascular remodeling were performed as well. RESULTS: Artery intimal proliferation progressed gradually as time went on, which was more significant in Group C as compared with that in Group B and D (P < 0.01). All the drugs could reduce the maximum intima thickness (MIT). Moreover, both high-dose XSC and Probucol profoundly decreased the intima area (IA), showing significant difference as compared with that in Group C (P < 0.01). The internal elastic laminal area (IELa), external elastic laminal area (EELa), minimum lumen diameter (MLD) and lumen area (LA) in Group A increased significantly, as compared with that in Group N (P < 0.01). At 6 weeks after balloon injury, with the further intimal thickening, IELa, EELa reduced contrarily, resulting in insufficient vascular compensation, lumen stricture and MLD reduction (P < 0.01). Improvement of MLD and LA was shown in all the drug treated groups, with significant difference in comparing with those in Group C (P < 0.01). CONCLUSION: Single endothelium injury may be one of the initiating elements of pathological vascular remodeling, which could be intensified by hyperlipemia. Intimal proliferation and vascular remodeling jointly participated in the pathological course of AS lumen stricture after endothelium injury. XSC plays its action in preventing and treating AS through inhibiting intimal proliferation after balloon injury and intervening pathological vascular remodeling.

Animals↗
PubMed2004

[Estrogen receptor alpha and colocalization of Bcl-2 in hippocampus of Alzheimer's disease].

OBJECTIVE: To investigate the possible mechanism by which estrogen regulates apoptosis through the estrogen receptor. METHODS: By means of fluorescence immunocytochemistry, the present study investigated the distribution of Bcl-2 and the colocolization of Bcl-2 and ERalpha immunoreactivity in the hippocampus of 10 Alzheimer's disease (AD) patients and 10 aged controls. RESULTS: Bcl-2 immunoreactivity was widely distributed in neurons, concentrating predominantly on the subfields CA3 and CA4 in the stratum pyramidale of hippocampus both in controls and in AD patients. Bcl-2 staining in the labeled neuron was observed mainly in the cytoplasm and neuritic processes, but a few nuclei were also positive. Bcl-2 labeling was also detected in the astrocytes mainly in AD, but sparsely in controls. Double-labeled fluorescence immunocytochemistry showed that most Bcl-2-immunolabeled neurons also exhibited positive staining for ERalpha. CONCLUSIONS: Estrogen may function as a regulator of apoptosis to modulate the expression of Bcl-2 in neurons and astrocytes in hippocampus of AD through ERalpha.

Alzheimer Disease↗
PubMed2004

Transcriptional gene expression profile of human nasopharynx.

Inflammation in the nasopharynx is very common worldwide and nasopharyngeal carcinoma (NPC) results in significant morbidity and mortality in southeast Asia and north Africa. To facilitate the understanding of pathogenesis of these diseases as well as normal nasopharynx biology, transcriptional gene expression profile of normal human nasopharynx, from undissected biopsies, was established in this study by generating a large amount of ESTs, followed by bioinformatics analysis. A total of 27,209 ESTs generated from human nasopharynx cDNA library were integrated into 8,420 non-redundant clusters, of which, 6,070 (72.09%) corresponded to known genes, 156 (1.85%) to known ESTs, and 2,194 (26.06%) to novel sequences, respectively. Functional classification revealed that transcripts constituting enzymes (2,284, 28.30%) and those participating in cell growth/maintenance (3,306, 46.33%) were the largest population expressed in the nasopharynx, followed by genes coding for binding proteins (2,135, 26.45%) and involved in cell communication process (1,832, 25.68%). In addition, through comparison of the nasopharynx gene expression profile with those of 7 other human tissues, 59 transcripts preferentially expressed and 22 transcripts unique in the nasopharynx were identified. Our study acquired an initial assessment of qualitative diversity of gene expression in the nasopharynx, providing the first step toward comprehensive characterization of the molecular features of the nasopharyngeal disorders.

Base Sequence↗
PubMed2004

[Dynamics of heat balance during growing season of broadleaved Korean pine forest in Changbai Mountains].

Based on the gradient measurement of microclimate factors, radiation and soil heat flux from late May to early October, 2001 and by the method of Bowen ratio-energy balance (BREB), this paper estimated the latent heat and sensible heat above the broadleaved Korean pine forest in Changbai Mountains. The energy storage of forest air and vegetative was calculated, and the seasonal variations of heat balance components of the forest were analyzed. The results showed that the net radiation of the forest and the solar radiation were linearly correlated. All the heat balance components had the similar characteristics of diurnal variation to the net radiation, showing curves positive at daytime and negative at night, and the terms ranged as net radiation > latent heat > sensible heat > storage. The time of keeping positive terms in a day became shorter from June to October as influenced by shinning time. The highest net radiation was in June and the lowest in October. The monthly averaged net radiation was 0-527 and 0-(-)121 W x m(-2), and the latent heat was 0-441 and 0-(-)81 W x m(-2) for day and night, respectively. Sensible heat was 0-80 and 0-(-)26 W x m(-2), and energy storage was 0-44 and 0-(-)26 W x m(-2) for day and night, respectively. The ratio of latent heat to net radiation at daytime decreased gradually from August to October, and the ratio of sensible heat and energy storage increased correspondingly. Especially 2-3 days after the first severe frost, a sudden drop of latent heat and a sudden bounce of sensible heat appeared. The instruments and measurement methods of heat flux were also concisely discussed in this paper.

China↗
PubMed2003

Regional alteration of synapsin I in the hippocampal formation of Alzheimer's disease patients.

Synapsin I is a synaptic vesicle-associated protein, participating in synapse formation, regulation of the synthesis of other synaptic vesicle proteins and promotion of neurotransmitter release. The aim of present study was to detect whether regional alteration of synapsin I occurred in the hippocampal formation of Alzheimer's disease (AD) patients. Samples of hippocampus from ten female AD patients and ten non-demented female controls, matched for age and postmortem delay, were investigated immunocytochemically. Using immunofluorescence labeling and laser confocal imaging, we examined the distribution of synapsin I in the CA1 and CA3 subfields of the hippocampus and the dentate gyrus (DG) in AD patients and controls. The results showed that synapsin I was significantly decreased in the stratum radiatum of CA1 subfield and the molecular layer of DG in AD patients. No difference between the two groups in the intensity of synapsin I staining was observed in the stratum pyramidale of CA1, where a number of pretangles stained by Alz-50 were observed in AD patients. These results suggest that there is regional loss of synapsin I in the hippocampal formation of AD patients.

Aged↗
PubMed2003

Characterization of soybean genomic features by analysis of its expressed sequence tags.

We analyzed 314,254 soybean expressed sequence tags (ESTs), including 29,540 from our laboratory and 284,714 from GenBank. These ESTs were assembled into 56,147 unigenes. About 76.92% of the unigenes were homologous to genes from Arabidopsis thaliana ( Arabidopsis). The putative products of these unigenes were annotated according to their homology with the categorized proteins of Arabidopsis. Genes corresponding to cell growth and/or maintenance, enzymes and cell communication belonged to the slow-evolving class, whereas genes related to transcription regulation, cell, binding and death appeared to be fast-evolving. Soybean unigenes with no match to genes within the Arabidopsis genome were identified as soybean-specific genes. These genes were mainly involved in nodule development and the synthesis of seed storage proteins. In addition, we also identified 61 genes regulated by salicylic acid, 1,322 transcription factor genes and 326 disease resistance-like genes from soybean unigenes. SSR analysis showed that the soybean genome was more complex than the Arabidopsis and the Medicago truncatula genomes. GC content in soybean unigene sequences is similar to that in Arabidopsis and M. truncatula. Furthermore, the combined analysis of the EST database and the BAC-contig sequences revealed that the total gene number in the soybean genome is about 63,501.

Chromosomes, Artificial, Bacterial↗
PubMed2003

Room-temperature preparation and characterization of poly (ethylene glycol)-coated silica nanoparticles for biomedical applications.

Monodisperse, spherical, polyethylene glycol (PEG)-coated silica nanoparticles have been prepared at room temperature and characterized for the purpose of biomedical applications. The particles were synthesized by the hydrolysis of tetramethyl orthosilicate (TMOS) in alcohol media under catalysis by ammonia, and their size can range from about 50-350 nm in diameter. We studied the particle size and size distribution using a scanning electron microscope (SEM) and an asymmetric field-flow fractionation (AFFF) multiangle static light-scattering instrument. The chemical and/or physical binding of PEG to the silica nanoparticles was studied by infrared spectroscopy, and the weight percentage of PEG attached to the particles was quantified. The PEG-coated silica nanoparticles showed enhanced colloidal stability when redispersed into aqueous solutions from the dried state as a result of the steric stabilization function of the PEG polymer grafted on the surface of particles. A nonspecific protein-binding test was also carried out to show that the PEG coating can help reduce the protein adsorption onto the surface of the particles, relating to the biocompatibility of these PEG-coated particles. Also, the inclusion of magnetic nanoparticles into the silica particles was shown as an example of the possible applications of PEG-coated silica particles. These silica nanoparticles, as a matrix for encapsulation of certain reagents, have potential for applications to in vivo diagnosis, analysis, and measurements inside intact biologic systems.

Biocompatible Materials↗
PubMed2003

Study on the complex site of L-tyrosine with rare-earth element Eu3+.

Amino acids are the primary units of proteins and play an important role in human life. The coordinate of L-tyrosine with rare-earth element Eu(3+) was investigated in solution by ultraviolet and was proved the molar ratio is 1:2. Then the solid complex was prepared by coprecipitation method. The complex was characterized by several analytical techniques, including Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Scanning Electron Microscopy, 1H-NMR and 13C-NMR. Based on these data, we found that pentatomic ring was formed by binding with N atom in group of amino (-NH(2)) and O atom in group of carboxyl (-COOH).

Binding Sites↗
PubMed2003

Neurotensin expressing neurons developed earlier than vasoactive intestinal polypeptide and vasopressin expressing neurons in the human suprachiasmatic nucleus.

Development of neurotensin (NT), vasoactive intestinal polypeptide (VIP), vasopressin (AVP) and neuropeptide-Y (NPY) expressing neurons was investigated in the human fetal suprachiasmatic nucleus of nine subjects ranging from 20-40 weeks of gestation using immunocytochemistry and morphometry. Results obtained showed that NT expressing neurons developed earlier than VIP, AVP and NPY expressing neurons. Consistent with results obtained from animal studies, we also found VIP expressing neurons were born earlier than AVP expressing neurons. Whether the NT expressing neurons play a role in generating circadian rhythms in the early life of humans needs to be further investigated.

Female↗
PubMed2003

Estrogen receptor alpha-immunoreactive astrocytes are increased in the hippocampus in Alzheimer's disease.

Postmenopausal estrogen use may decrease the risk, and delay the onset and progression, of Alzheimer's disease (AD). By means of fluorescence immunocytochemistry, the present study investigated the distribution of estrogen receptor alpha (ERalpha) in the human hippocampus in controls and in AD cases. ERalpha immunoreactivity was observed in neurons and glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes in the hippocampus both in controls and AD cases. The number and density of GFAP- and ERalpha-positive astrocytes was increased in AD. The number of GFAP-immunoreactive astrocytes, the number of nuclear ERalpha-staining astrocytes, and cytoplasmic ERalpha-staining astrocytes per unit area (1 mm(2)) significantly increased (P < 0.001, P < 0.05, P < 0.05, respectively) in CA1 in AD patients, while the percentage of ERalpha-immunoreactive astrocytes of the two groups did not differ (P > 0.05). These data suggest an important role for ERalpha-mediated effects of estrogens on neurons and astrocytes in the hippocampus of human and AD patients.

Aged↗
PubMed2003

Gene identification and expression analysis of 86,136 Expressed Sequence Tags (EST) from the rice genome.

Expressed Sequence Tag (EST) analysis has pioneered genome-wide gene discovery and expression profiling. In order to establish a gene expression index in the rice cultivar indica, we sequenced and analyzed 86,136 ESTs from nine rice cDNA libraries from the super hybrid cultivar LYP9 and its parental cultivars. We assembled these ESTs into 13,232 contigs and leave 8,976 singletons. Overall, 7,497 sequences were found similar to existing sequences in GenBank and 14,711 are novel. These sequences are classified by molecular function, biological process and pathways according to the Gene Ontology. We compared our sequenced ESTs with the publicly available 95,000 ESTs from japonica, and found little sequence variation, despite the large difference between genome sequences. We then assembled the combined 173,000 rice ESTs for further analysis. Using the pooled ESTs, we compared gene expression in metabolism pathway between rice and Arabidopsis according to KEGG. We further profiled gene expression patterns in different tissues, developmental stages, and in a conditional sterile mutant, after checking the libraries are comparable by means of sequence coverage. We also identified some possible library specific genes and a number of enzymes and transcription factors that contribute to rice development.

Arabidopsis↗
PubMed2003

EST pipeline system: detailed and automated EST data processing and mining.

Expressed sequence tags (ESTs) are widely used in gene survey research these years. The EST Pipeline System, software developed by Hangzhou Genomics Institute (HGI), can automatically analyze different scalar EST sequences by suitable methods. All the analysis reports, including those of vector masking, sequence assembly, gene annotation, Gene Ontology classification, and some other analyses, can be browsed and searched as well as downloaded in the Excel format from the web interface, saving research efforts from routine data processing for biological rules embedded in the data.

Automation↗
PubMed2003

Differentially expressed downstream genes in cells with normal or mutated p53.

Mutations in p53 gene could lead to loss of function, negative complementation, or to gain-of-oncogenic functions, thus leading to the increase of tumorigenicity and invasiveness of cancer. This study focused on cancer-related p53 mutants, including A138T, C141Y, RI58L, G245C, and R248Q. Using a modified differential display technique, response profiles of plasmid-expressed wild-type as well as mutated p53, in comparison to p53-null cells, are being established. These profiles can help our understanding of p53 involvement in cancer, leading to accurate diagnosis, treatment, and prognostic analysis by: 1) comprehensive knowledge of p53 network gene expression profiles; 2) finding the most significant gene expression profiles of p53 mutants; 3) revealing genes that only respond to p53 mutants (gain of function). Our results showed significant differences in the expression patterns among p53-null. wild-type p53, and p53 mutants A138T, C141Y, R158L, G245C, and R248Q samples. We also report here the first found p53 mutant-triggered alternative splicing.

Alternative Splicing↗