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Biomedical subjects

Q Gao

Publications and source records attributed to Q Gao.

At least 19 recordsLinked to original sources
PubMed2006

Phylogeny of diplozoids in five genera of the subfamily Diplozoinae Palombi, 1949 as inferred from ITS-2 rDNA sequences.

The phylogenetic relationship of 5 genera, i.e. Diplozoon Nordmann, 1832, Paradiplozoon Achmerov, 1974, Inustiatus Khotenovsky, 1978, Sindiplozoon Khotenovsky, 1981, and Eudiplozoon Khotenovsky, 1985 in the subfamily Diplozoinae Palombi, 1949 (Monogenea, Polyopisthocotylea) was inferred from rDNA ITS-2 region using neighbour-joining (NJ), maximum likelihood (ML) and Bayesian methods. The phylogenetic trees produced by using NJ, ML and Bayesian methods exhibit essentially the same topology. Surprisingly, freshwater species of Paradiplozoon from Europe clustered together with species of Diplozoon, but separated from Chinese Paradiplozoon species. The results of molecular phylogeny and lower level of divergence (4.1-15.7%) in ITS-2 rDNA among Paradiplozoon from Europe and Diplozoon and, on the other hand, high level of divergence (45.3-53.7%) among Paradiplozoon species from Europe and China might indicate the non-monophyletic origin of the genus Paradiplozoon. Also, the generic status of European Paradiplozoon needs to be revised. The species of Paradiplozoon in China is a basal group in Diplozoinae as revealed by NJ and Bayesian methods, and Sindiplozoon appears to be closely related to European Paradiplozoon and Diplozoon with their relationship to Eudiplozoon and Inustiatus being unresolved.

Animals↗
PubMed2006

Interception of residual nitrate from a calcareous alluvial soil profile on the North China Plain by deep-rooted crops: a 15N tracer study.

15N-labeled nitrate was injected into different depths of an alluvial calcareous soil profile on the North China Plain. Subsequent movement of NO3- -N and its recovery by deep-rooted maize (Zea mays L.) and shallow-rooted eggplant (Solanum melongena L.) were studied. Under conventional water and nutrient management the mean recoveries of 15N-labeled nitrate from K(15)NO3 injected at depths 15, 45, and 75 cm were 22.4, 13.8, and 7.8% by maize and 7.9, 4.9, and 2.7% by eggplant. The recovery rate by maize at each soil depth was significantly higher than by eggplant. The deeper the injection of nitrate the smaller the distance of its downward movement and this corresponded with the movement of soil water during crop growth. Deeper rooting crops with high root length density and high water consumption may therefore be grown to utilize high concentrations of residual nitrate in the subsoil from previous intensive cropping and to protect the environment.

Biomass↗
PubMed2006

Expression of 2',3'-cyclic nucleotide 3'-phosphodiesterase in the amoeboid microglial cells in the developing rat brain.

Expression of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in amoeboid microglial cells (AMC) in developing rat brain from prenatal day 18 (E18) to postnatal day 10 (P10) was demonstrated by immunohistochemistry/immunofluorescence and immunoelectron microscopy both in vivo and in vitro, respectively. Furthermore, real time-polymerase chain reaction (PCR) was performed to determine the expression of CNPase at mRNA level in cultured microglial cells in control conditions and following lipopolysaccharide stimulation. CNPase immunoreactive amoeboid microglia occurred in large numbers in the corpus callosum, subventricular zone and cavum septum pellucidum at P0 but were progressively reduced with age and were undetectable at P14. By immunoelectron microscopy, immunoreaction product was associated primarily with the plasma membrane, filopodial projections and mitochondria in AMC. Real time-PCR analysis revealed that CNPase mRNA was expressed by cultured amoeboid microglia and was significantly up-regulated in microglial activation induced in vitro by lipopolysaccharide. The functional role of CNPase in AMC remains speculative. Given its expression in AMC transiently occurring in the perinatal brain and that it is markedly elevated in activated microglia, it is suggested that the enzyme may be linked to the major functions of the cell type such as release of chemokines and cytokines. In relation to this, CNPase may play a key role associated with transportation of cytoplasmic materials.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed2006

Oncolytic adenovirus-mediated transfer of the antisense chk2 selectively inhibits tumor growth in vitro and in vivo.

Screening and identifying molecules target to checkpoint pathways has fostered the development of checkpoint-based anticancer strategies. Among these targets, inhibition of chk2 may induce cell death for tumors whose growth depends on enhanced chk2 activity. However, improvement of the potency and specificity of such therapeutics remains a major challenge. To resolve this problem, we constructed M3, a novel recombinant adenovirus with a 27-bp deletion in E1A CR2 region by which to realize tumor-specific replication, and an 829-bp of antisense chk2 fragment inserted into the E3 coding region. In this design, M3 exploited the native adenovirus E3 promoters to express antisense chk2 cDNA in a viral replication-dependent fashion, and preferentially silenced the chk2 gene in tumor cells. In vitro and in vivo assays confirmed that downregulated chk2 expression induced by M3 infection was tumor-specific and virus replication-dependent. Furthermore, systemic administration of M3 combined with a low dose of cisplatin cured 75% (9/12) of orthotopic hepatic carcinoma mouse models that were otherwise resistant to cisplatin. Our results indicated that the upcoming development in this field would improve the antitumor efficacy and maximize the synergistic effect of oncolytic viruses administered with traditional chemotherapy or radiotherapy.

Adenoviridae↗
PubMed2006

Bone marrow stromal cells upregulate expression of bone morphogenetic proteins 2 and 4, gap junction protein connexin-43 and synaptophysin after stroke in rats.

Bone morphogenetic proteins play a key role in astrocytic differentiation. Astrocytes express the gap junctional protein connexin-43, which permits exchange of small molecules in brain and enhances synaptic efficacy. Bone marrow stromal cells produce soluble factors including bone morphogenetic protein 2 and bone morphogenetic protein 4 (bone morphogenetic protein 2/4) in ischemic brain. Here, we tested whether intra-carotid infusion of bone marrow stromal cells promotes synaptophysin expression and neurological functional recovery after stroke in rats. Adult male Wistar rats were subjected to 2 h of right middle cerebral artery occlusion. Rats were treated with or without bone marrow stromal cells at 24 h after middle cerebral artery occlusion via intra-arterial injection (n=8/group). A battery of functional tests was performed. Immunostaining of 5-bromo-2-deoxyuridine, Ki67, bone morphogenetic protein 2/4, connexin-43, synaptophysin, glial fibrillary acidic protein, neuronal nuclear antigen, and double staining of 5-bromo-2-deoxyuridine/glial fibrillary acidic protein, 5-bromo-2-deoxyuridine/neuronal nuclear antigen, glial fibrillary acidic protein/bone morphogenetic protein 2/4 and glial fibrillary acidic protein/connexin-43 were employed. Rats treated with bone marrow stromal cells significantly (P<0.05) improved functional recovery compared with the controls. 5-Bromo-2-deoxyuridine and Ki67 positive cells in the ipsilateral subventricular zone were significantly (P<0.05) increased in bone marrow stromal cell treatment group compared with the controls, respectively. Administration of bone marrow stromal cells significantly (P<0.05) promoted the proliferating cell astrocytic differentiation, and increased bone morphogenetic protein 2/4, connexin-43 and synaptophysin expression in the ischemic boundary zone compared with the controls, respectively. Bone morphogenetic protein 2/4 expression correlated with the expression of connexin-43 (r=0.84, P<0.05) and connexin-43 expression correlated with the expression of synaptophysin (r=0.73, P<0.05) in the ischemic boundary zone, respectively. Administration of bone marrow stromal cells via an intra-carotid route increases endogenous brain bone morphogenetic protein 2/4 and connexin-43 expression in astrocytes and promotes synaptophysin expression, which may benefit functional recovery after stroke in rats.

Analysis of Variance↗
PubMed2006

DSS1 is required for the stability of BRCA2.

DSS1 is an evolutionarily conserved acidic protein that binds to BRCA2. However, study of the function of DSS1 in mammalian cells has been hampered because endogenous DSS1 has not been detectable by Western blotting. Here, we developed a modified Western blotting protocol that detects endogenous DSS1 protein, and used it to study the function of DSS1 and its interaction with BRCA2 in mammalian cells. We found that essentially all BRCA2 in human cell lines is associated with DSS1. Importantly, we found that RNAi knockdown of DSS1 in human cell lines led to dramatic loss of BRCA2 protein, mainly due to its increased degradation. Furthermore, the stability of BRCA2 mutant devoid of the DSS1-binding domain is unaffected by the depletion of DSS1. Most notably, like BRCA2 depletion, DSS1 depletion also led to hypersensitivity to DNA damage. These results demonstrated that the stability of BRCA2 protein in mammalian cells depends on the presence of DSS1. Deletion or mutation of DSS1 or suppression of its expression by other mechanisms are therefore potential causative mechanisms for human breast and ovarian cancer. Such mechanisms may be relevant to sporadic as well as familiar breast cancer where BRCA1 and BRCA2 mutations are not present.

BRCA2 Protein↗
PubMed2006

Inhibition of ovarian cancer metastasis by adeno-associated virus-mediated gene transfer of nm23H1 in an orthotopic implantation model.

Ovarian cancer is one of the most threatening malignant tumors in females due to the frequent occurrence of metastasis that precedes diagnosis. The present study explored the possibility of preventing ovarian cancer metastasis by promoting nm23H1 expression through adeno-associated virus (AAV)-mediated gene transfer. A cell line of high metastatic potential, SW626-M4, was derived by in vivo selection and used to establish an ovarian cancer metastasis model in the mouse. Liver metastasis and animal survival time were measured after transfer of a recombinant adeno-associated viral vector expressing nm23H1 (AAV-nm23H1) into the aforementioned model. Intraperitoneal injection of AAV-nm23H1 into this orthotopic implantation model of ovarian cancer resulted in (1) expression of the exogenous gene in more than 95% of tumor cells in situ in nude mice; (2) a 60% reduction in the number of animals developing liver metastases; and (3) a 35-day prolongation of median survival time compared with the untreated host group. In conclusion, the results support the feasibility of induction of nm23H1 expression through gene transfer as a therapeutic strategy for preventing metastases and prolonging host survival time, and indicate that AAV vectors deserve attention in the design of future gene therapy approaches to achieving long-term expression of curative genes in vivo.

Adenocarcinoma↗
PubMed2006

Changes in serum cardiac troponins following a 21-km run in junior male runners.

AIM: This study was designed to examine the appearance and clearance characteristics of serum cardiac troponin T (cTnT) and I (cTnI) in junior runners after an exhaustive 21-km run. The dependence of the alternations of the cardiac troponins on the runners' training status reflected in training years, running ability and physiological profile at ventilatory threshold (Th(vent)) was also examined. METHODS: Ten trained male adolescents (16.2+/-0.6 years) performed 21-km run and graded treadmill exercise with maximum effort on two different days. cTnT and cTnI immediately before and 2, 4 and 24 hours after exercise were measured in the 21-km trial. The parameters at Thvent including the running speed (Th(vent)-Speed) and VO2 (Th(vent)-VO2) were identified in the graded exercise trial. RESULTS: Serum cTnT and cTnI in 6 of the 10 subjects measured 4 hours after the 21-km run were above the myocardial injury cutoffs of 0.03 and 0.09 ng x mL(-1), respectively, but returned towards pre-exercise levels within 24 hours that were not in the same manner observed in the clinical situation of myocardial infraction. The 6 subjects' training status was generally lower than that of the rest 4. Further, subjects' 4-h serum cTnT and cTnI were negatively related to their training years, Th(vent)-Speed and Th(vent)-VO2, and positively related to their personal best in half- and full-marathon races (r2 = or > 36%, n = 10). CONCLUSIONS: Such findings implied that clinicians based the diagnosis of long-distance run-induced myocardial infraction in novice junior runners upon the transient postexercise elevations of cardiac troponins alone should be with caution.

Adolescent↗
PubMed2005

Bacterial insertion sequence IS256 as a potential molecular marker to discriminate invasive strains from commensal strains of Staphylococcus epidermidis.

The skin commensal Staphylococcus epidermidis has become one of the most important causative agents of nosocomial infections associated with medical devices. Differentiation between invasive S. epidermidis and its commensal counterpart is crucial for clinical decision making. The ica gene locus, which codes for production of polysaccharide intercellular adhesion (PIA), represents a frequently suggested molecular marker for infectivity. Our data demonstrated that production of PIA was not significantly increased among clinical strains, which may explain the controversial results obtained previously on the correlation of ica presence with origin from infection. Therefore, in this study, we attempted to identify novel genes discriminating between invasive and commensal strains based on the comparison of genome sequences. Our results indicated that the bacterial insertion sequence element IS256 occurred significantly more frequently in strains of clinical origin. Importantly, IS256 might thus constitute a molecular marker to discriminate invasive strains from commensal strains of S. epidermidis.

Carrier State↗
PubMed2005

Bone marrow stromal cells increase astrocyte survival via upregulation of phosphoinositide 3-kinase/threonine protein kinase and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathways and stimulate astrocyte trophic factor gene expression after anaerobic insult.

Transplantation of bone marrow stromal cells improves animal neurological functional recovery after stroke. Astrocytes are known to provide structural, trophic and metabolic support for neurons. Thus astrocytes are critical for neural survival during post-ischemia. However, information on the effects of bone marrow stromal cells on astrocytic survival post-ischemia is unavailable. We investigated the influence of rat bone marrow stromal cells on rat astrocytic apoptosis and survival post-ischemia employing an anaerobic chamber. Our data indicate that rat bone marrow stromal cells reduce cell death and apoptosis, and increase the DNA proliferation rate in astrocytes post-ischemia. Mitogen-activated protein kinase kinase/extracellular signal regulated kinase and phosphoinositide 3-kinase/threonine protein kinase pathways are involved in cell survival. Western blot showed that rat bone marrow stromal cells activate these two pathways in astrocytes post-ischemia, and upregulate total extracellular signal regulated kinase 1/2 and threonine protein kinase. Since astrocytes produce various neurotrophic factors, we performed reverse transcription polymerase chain reaction to investigate rat bone marrow stromal cells' effect on astrocyte growth factor gene expression post-ischemia. We observed that brain-derived neurotrophic factor, vascular endothelial growth factor and basic fibroblast growth factor gene expression was enhanced by rat bone marrow stromal cell coculture. These data suggest that bone marrow stromal cells increase astrocytic survival post-ischemic injury. This protective function might involve the activation of mitogen-activated protein kinase kinase/extracellular signal-regulated kinase and phosphoinositide 3-kinase/threonine protein kinase pathways. Upregulation of brain-derived neurotrophic factor, vascular endothelial growth factor and basic fibroblast growth factor may also contribute to astrocyte survival.

Anaerobiosis↗
PubMed2005

Hydrogen-bonding interactions in acetic acid monohydrates and dihydrates by density-functional theory calculations.

Equilibrium structures and the respective binding energies of acetic acid monohydrates and dihydrates have been determined by density-functional theory calculations with different basis sets, including 6-31+G(3d,p), 6-311++G(d,p), and 6-311++G(3df,3pd). Given that the C=O and OH groups in acetic acid provide the predominant hydrogen-bonding interactions with water, six stable conformer structures have been found each for the monohydrate and syn-dihydrate. Of the three syn- and three anti-conformers of acetic acid with water, the most stable monohydrate structure is found to be that of the syn-conformer bonding with water in a cyclic double H-bonded geometry. Similarly, the syn-conformer bonding with two water molecules in a cyclic double H-bonded geometry has also been determined to be the most stable among the six plausible structures for the syn-dihydrate. Frequency analysis of the stable conformers has been performed and the vibrational spectra of the most stable monohydrate and dihydrate structures are compared with the experimental gas-phase and matrix data. Furthermore, the calculated binding energies between an acetic acid and a water molecule for both monohydrate and dihydrate are larger than that between two water molecules, which supports our recent experimental observation of coevaporation of acetic acid with water upon annealing acetic acid on ice.

Journal Article↗
PubMed2005

Thermal evolution of acetic acid nanodeposits over 123-180 K on noncrystalline ice and polycrystalline ice studied by FTIR reflection-absorption spectroscopy: hydrogen-bonding interactions in acetic acid and between acetic acid and ice.

Acetic acid vapor-deposited on ultrathin noncrystalline ice (NCI) and polycrystalline ice (PCI) films (less than 6 nm thick) under ultrahigh vacuum conditions has been investigated by using Fourier Transform Infrared Reflection-Absorption Spectroscopy. Pristine acetic acid deposited at 123 K (on a copper support) appears as an amorphous solid, which undergoes an irreversible phase transformation to a more structurally ordered (polycrystalline) form upon annealing to 153 K. Acetic acid is found to adsorb on NCI and PCI films initially through hydrogen bonding between C=O and dangling OH (of ice), followed by the formation of multilayers at 123 K. Thermal evolution studies of a low exposure of acetic acid on the ultrathin NCI and PCI films show that acetic acid undergoes coevaporation with water likely as an acetic acid hydrate at 155 K, which continues until the entire ice film has been exhausted at 165 K. Above 165 K, the remaining acetic acid solid appears to evaporate without undergoing the phase transformation, in contrast to the case of a high acetic acid exposure. Coevaporation of acetic acid with water is also found to proceed at a faster rate than the subsequent evaporation of acetic acid, which is consistent with the weaker interactions observed in the H-bonded acetic acid hydrate than that in acetic acid solid.

Journal Article↗
PubMed2005

Identification of immune genes in grass carp Ctenopharyngodon idella in response to infection of the parasitic copepod Sinergasilus major.

The parasitic copepod Sinergasilus major is an important pathogen of grass carp Ctenopharyngodon idella. To understand the immune response of grass carp to the copepod infection, suppression subtractive hybridization method was employed to characterize genes up-regulation during the copepod infection in liver and gills of the fish. One hundred and twenty-two dot blot positive clones from infected subtracted library were sequenced. Searching available databases by using these nucleotide sequences revealed that 23 genes are immune-related, including known acute-phase reactants, and four novel genes encoding proteins such as source of immunodominant MHC-associated peptides (SIMP), TNF receptor-associated factor 2 binding protein (T2BP), poliovirus receptor-related protein 1 precursor, glycoprotein A repetitions predominant (GARP). The differential expression of seven immune genes, i.e. GARP, alpha-2-macroglobulin, MHC class I, C3, SIMP, T2BP, transferrin, as a result of infection was further confirmed by RT-PCR, with the up-regulation of alpha-2-macroglobulin, MHC class I, C3, SIMP and T2BP in the liver of infected fish, and down-regulation of SIMP in the gills of infected fish. The present study provides foundation for understanding grass carp immune response and candidate genes for further analysis.

Animals↗
PubMed2005

Expression of matrix metalloproteinases-2 and -9 in intestinal tissue of patients with inflammatory bowel diseases.

BACKGROUND/AIMS: Matrix metalloproteinases are major contributors in the breakdown and reconstitution of basement membranes and extracellular matrix in pathophysiological processes. We assessed the expression of matrix metalloproteinases-2 and -9 in intestinal tissue of patients with inflammatory bowel disease. PATIENTS/METHODS: Resected tissue specimens from patients with Crohn's disease or ulcerative colitis and control tissue from patients with a colorectal carcinoma were used for enzyme-linked immunosorbent assay, zymography, activity assay, reverse transcription polymerase chain reaction and immunohistochemistry to evaluate the expression of these matrix metalloproteinases. RESULTS: Matrix metalloproteinase-2 and more strongly matrix metalloproteinase-9 protein and mRNA were markedly increased in inflammatory bowel disease tissues, with the highest levels in severely inflamed tissues. Immunohistochemistry showed that matrix metalloproteinase-2 was present in the extracellular matrix of the submucosa, with a lower but more generalised expression in the severely inflamed regions. Matrix metalloproteinase-9 was most prominent in polymorphonuclear leukocytes and was increased, also in activity, in all inflammatory bowel disease tissues. An increased matrix metalloproteinase-9 expression in the extracellular matrix was observed in relation to the severity of inflammation. CONCLUSIONS: Matrix metalloproteinases-2 and -9 are enhanced in the intestinal tissue and seem to be actively involved in the inflammatory and remodelling processes in inflammatory bowel disease, without major differences between CD and UC.

Adult↗
PubMed2005

Genetic diagnosis of PLP gene duplications/deletions in patients with Pelizaeus-Merzbacher disease.

Genetic diagnosis of PLP gene duplications/deletions in patients with Pelizaeus-Merzbacher disease.PMD is an X-linked recessive disorder due to a proteolipid protein (PLP) deficiency. Duplications of PLP gene were shown to be the principle cause of the disorder, accounting for an estimated 50-70% of cases. To define a simple and reliable method for genetic diagnosis of PMD, a group of 42 patients with clinical manifestation of PMD was analyzed by means of real-time quantitative PCR. Parallel fluorescence in situ hybridization (FISH) analysis was performed on the same group of patients. Real-time PCR found seventeen samples had increased gene dosage, whereas FISH detected sixteen duplicated samples. Both methods identified a sample with PLP gene deletion. Our results indicate that real-time PCR is a sensitive and reliable method for the detection of gene duplications/deletions. We further discussed the advantages and limitations of each method in clinical diagnosis of PMD.

DNA Mutational Analysis↗
PubMed2005

Designing a framework of intelligent information processing for dentistry administration data.

OBJECTIVES: This study was designed to test a cumulative view of current data in the clinical database at the Faculty of Dentistry, Dalhousie University. We planned to examine associations among demographic factors and treatments. METHODS: Three tables were selected from the database of the faculty: patient, treatment and procedures. All fields and record numbers in each table were documented. Data was explored using SQL server and Visual Basic and then cleaned by removing incongruent fields. After transformation, a data warehouse was created. This was imported to SQL analysis services manager to create an OLAP (Online Analytic Process) cube. RESULTS: The multidimensional model used for access to data was created using a star schema. Treatment count was the measurement variable. Five dimensions--date, postal code, gender, age group and treatment categories--were used to detect associations. Another data warehouse of 8 tables (international tooth code # 1-8) was created and imported to SAS enterprise miner to complete data mining. Association nodes were used for each table to find sequential associations and minimum criteria were set to 2% of cases. Findings of this study confirmed most assumptions of treatment planning procedures. There were some small unexpected patterns of clinical interest. Further developments are recommended to create predictive models. CONCLUSIONS: Recent improvements in information technology offer numerous advantages for conversion of raw data from faculty databases to information and subsequently to knowledge. This knowledge can be used by decision makers, managers, and researchers to answer clinical questions, affect policy change and determine future research needs.

Adolescent↗
PubMed2005

Molecular epidemiology of Mycobacterium tuberculosis in China: a nationwide random survey in 2000.

OBJECTIVE: To determine the contribution of the Mycobacterium tuberculosis (TB) Beijing genotype to the population structure of M. tuberculosis complex in China. DESIGN: Genotypes of 441 mycobacterial isolates were determined by spoligotyping and IS6110 restriction fragment length polymorphism (RFLP). The isolates were from a nationwide random survey for the epidemiology of TB conducted in 2000, and the drug susceptibility patterns and epidemiological data were known. RESULT: A total of 408 samples contained M. tuberculosis as determined by spoligotyping. Of the M. tuberculosis strains, 64.9% (265/408) were of the Beijing genotype. Using the chi-squared test, no statistically significant differences were observed in the proportion of Beijing genotype TB in patients of different sex, age or living in different areas of the country, but a significant difference was observed with multidrug-resistant (MDR) TB: 77.8% (42/ 54) of MDR isolates were of the Beijing genotype vs. 60.2% (213/354) of the drug-susceptible isolates. In the multivariate logistic regression model, the Beijing genotype was significantly associated with region and not with MDR. CONCLUSION: The M. tuberculosis Beijing genotype has prevailed in China for at least five decades and is associated with region.

Adolescent↗