Biomedical subjects

Q Gu

Publications and source records attributed to Q Gu.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Preparation of green fluorescent protein retrovirus and its application in mediating gene transfer into retinal pigment epithelial cells].

OBJECTIVE: To determine whether human retinal pigment epithelial (RPE) cells can be infected by retrovirus and modified by retrovirus-mediated gene transfer. METHODS: Recombination retroviral vector pLNCX-GFP (green fluorescent protein, GFP) was generated by inserting 780 bp GFP cDNA fragment into the MCS site of pLNCX. pLNCX-GFP was transfected into ecotropic packaging cell line PhiX-Eco and amphotropic packaging cell line PhiX-Ampho and PA317. Retroviral titer was tested by counting GFP expression of NIH3T3 cells. Then RPE cells were infected by using GFP retrovirus-containing supernatant. RESULTS: GFP was expressed and retrovirus was produced upon pLNCX-GFP being transfected into packaging cell line. The GFP retrovirus was able to infect primary cultured human RPE cells and immortalized RPE cell line. CONCLUSION: The retrovirus can introduce a foreign gene into RPE cells efficiently, thereby it can be used as an important tool to deliver gene into RPE for therapy of fundus diseases.

Cells, Cultured↗

PubMed2000

Activity-dependent and use-dependent regulation of dopamine-receptor clustering.

In this study, fluorescence-conjugated ligands were employed to label dopaminergic D1-like and D2-like receptors, respectively, in neurons derived from the frontal cortex of embryonic rats. The receptor binding sites were visualized and analyzed using confocal microscopy. Our results showed that fluorescently labeled receptors tended to form clusters with a diameter of about one micrometer and were distributed on both somata and dendrites. Chronic treatment with tetrodotoxin reduced the number of fluorescent clusters of both D1-like and D2-like receptors, while chronic treatment with a high concentration of potassium increased the number of fluorescent clusters of both D1-like and D2-like receptors. Further, chronic treatment with SCH23390 up-regulated the number of D1-like receptor clusters, whereas chronic treatment with bromocriptine down-regulated the number of D2-like receptor clusters. In addition, chronic treatment with spiperone down-regulated the number of D1-like receptor clusters. These results suggest that both neuronal activity and dopaminergic receptor occupancy are important factors that determine dopaminergic receptor clustering which is an essential step toward synaptogenesis during neuronal maturation process.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed2000

Interaction of the tumor suppressor PTEN/MMAC with a PDZ domain of MAGI3, a novel membrane-associated guanylate kinase.

PTEN/MMAC is a phosphatase that is mutated in multiple human tumors. PTEN/MMAC dephosphorylates 3-phosphorylated phosphatidylinositol phosphates that activate AKT/protein kinase B (PKB) kinase activity. AKT/PKB is implicated in the inhibition of apoptosis, and cell lines and tumors with mutated PTEN/MMAC show increased AKT/PKB kinase activity and resistance to apoptosis. PTEN/MMAC contains a PDZ domain-binding site, and we show here that the phosphatase binds to a PDZ domain of membrane-associated guanylate kinase with inverted orientation (MAGI) 3, a novel inverted membrane-associated guanylate kinase that localizes to epithelial cell tight junctions. Importantly, MAGI3 and PTEN/MMAC cooperate to modulate the kinase activity of AKT/PKB. These data suggest that MAGI3 allows for the juxtaposition of PTEN/MMAC to phospholipid signaling pathways involved with cell survival.

Amino Acid Sequence↗

PubMed2000

Quantitative expression analysis of genes regulated by both obesity and leptin reveals a regulatory loop between leptin and pituitary-derived ACTH.

Absence of the hormone leptin leads to dramatic increases in appetite, food intake, and adiposity. The primary site of action, at least with respect to appetite, is the hypothalamus. Leptin also has significant effects on the function(s) of peripheral organs involved in maintaining body composition. Some of these effects are mediated through direct interaction of leptin with its receptor on the target tissue, and some effects are indirectly mediated through secondary hormonal and neural pathways. Few of the genes that are responsible for regulating body composition and the peripheral effects of leptin are known. We have used a new gene profiling technology to characterize gene expression changes that occur in the pituitary, hypothalamus, fat, muscle, and liver in response to both obesity and treatment with exogenous leptin. These differences were then overlaid to allow the identification of genes that are regulated by obesity and at least partially normalized by leptin treatment. By using this process we have identified five genes (POMC, PC2, prolactin, HSGP25L2G, and one novel) that are both abnormally expressed in the pituitaries of obese mice and are sensitive to the effects of leptin. We also show that adrenocorticotropic hormone appears to be involved in a regulatory loop involving leptin.

Adipose Tissue↗

PubMed2000

Columnar distribution of serotonin-dependent plasticity within kitten striate cortex.

Recent studies have identified the potential for an important role for serotonin (5-HT) receptors in the developmental plasticity of the kitten visual cortex. 5-HT(2C) receptors are transiently expressed in a patchy fashion in the visual cortex of kittens between 30-80 days of age complementary to patches demarcated by cytochrome oxidase staining. 5-HT, operating via 5-HT(2C) receptors, increases cortical synaptic plasticity as assessed both in brain slices and in vivo. Herein, we report that bath application of 5-HT substantially increases the probability of long-term potentiation within 5-HT(2C) receptor-rich zones of cortex, but this effect is not observed in the 5-HT(2C) receptor-poor zones. Instead, in these zones, 5-HT application increases the probability of long-term depression. These location-specific effects of 5-HT may promote the formation of compartment-specific cortical responses.

Acetylcholinesterase↗

PubMed2000

Confocal imaging of N-methyl-D-aspartate receptors in living cortical neurons.

The fluorescence-conjugated N-methyl-D-aspartate receptor-selective antagonist, BODIPY-conantokin-G, was employed to label N-methyl-D-aspartate receptors in living neurons derived from the visual cortex of embryonic rats. The fluorescent labeling was visualized and analysed using confocal microscopy and digital imaging techniques. BODIPY-conantokin-G binding sites were homogeneously distributed across somata four days after neurons (E17-20) were placed in culture. In five-day-old cultures, BODIPY-conantokin-G binding sites became clusters of fluorescently labeled spots which were arranged irregularly on somata and proximal neurites. Distal neurites displayed fluorescent labeling after 10-15 days in culture. Displacement experiments showed that spermine and unlabeled conantokin-G compete with BODIPY-conantokin-G labeling at the N-methyl-D-aspartate receptor-associated polyamine site. The N-methyl-D-aspartate receptor antagonist 2-amino-5-phosphonovaleric acid also depressed the labeling but with a weaker effect, probably due to interactions occurring between the N-methyl-D-aspartate receptor agonist binding site and the polyamine modulatory site. The fluorescent dyes FM 1-43 and FM 4-64 were used in double-labeling studies to compare the distribution of nerve terminals with that of BODIPY-conantokin-G binding sites. BODIPY-conantokin-G binding clusters were associated with presynaptic nerve terminals while isolated BODIPY-conantokin-G binding sites were not always opposed to terminals. The aggregation of receptors to form clusters may lead to the functional formation of excitatory synapses. To investigate whether modulation of membrane potentials affected the formation of N-methyl-D-aspartate receptor clusters, cultured neurons were chronically treated for a week with either tetrodotoxin (to block membrane action potentials) or a high concentration of potassium to depolarize the membrane. While neurons in the tetrodotoxin-treated group showed a similar number of fluorescently labeled clusters compared with the control group, neurons in the high potassium group exhibited a higher number of fluorescently labeled receptor clusters. These results suggest that more active neurons may tend to form more N-methyl-D-aspartate synapses during early development.

Age Factors↗

PubMed2000

Development of antirotavirus agents in Asia.

Human rotaviruses are the major etiologic agents of diarrhea in infants and young children under 2 years of age worldwide. Rotavirus diarrhea is a life-threatening disease for children; many efforts are made to reduce the morbidity and mortality in Asia. To date many natural compounds and some Western medicines have exhibited their antirotavirus effects in clinical studies, in animal experiments and in vitro. Compared with antirotavirus agents in the USA and Europe, natural compounds have been identified as ideal candidates for antirotaviral drugs in Asia because they are cheaper and effective, have no side-effect and no toxicity. We have attempted to reveal the antirotavirus mechanism of some natural compounds. We found that cacao pigment, tea extract and pine seed shell extract inhibit rotavirus adsorption to cells while cacao pigment may also inhibit rotavirus reproduction in vitro. The usage of antirotavirus agents in Asia demonstrated that additional effective approaches to control rotavirus infection, such as antirotavirus agents, are necessary, in particular for the children with rotavirus diarrhea who have severe complications.

Antiviral Agents↗

PubMed2000

Localization and characterization of urocortin during human pregnancy.

Urocortin, a recently identified peptide of the corticotropin releasing hormone (CRH) peptide family, has potent vasodilatory effects in the human fetal placental circulation in vitro, promoting us to hypothesize that urocortin is produced locally to regulate uteroplacental vascular tone during pregnancy. In the present study, we examined the distribution of urocortin in the human placenta, fetal membranes and uterine tissue at term in the presence and absence of labour, using a urocortin antibody produced in our laboratory and the immunoperoxidase staining method. Immunoreactive (IR)-urocortin was observed in the vascular smooth muscle of the myometrium (n=5), decidual stromal cells, syncytiotrophoblast and amnion epithelium (n=10). No differences in staining intensity for urocortin were detected between tissues obtained in the absence (n=5) or presence (n=5) of labour. Staining intensity for IR-urocortin was greatest in the decidua suggesting this may be a site of urocortin production during pregnancy. Subsequently, we tested urocortin secretion from chorio-decidual cells in vitro, using an immunoblot technique. Positive staining for urocortin was observed in 40 per cent of chorio-decidual cells with 34 per cent of these cells secreting urocortin under basal conditions. Since urocortin was secreted by decidual cells we questioned whether urocortin was present in maternal plasma throughout gestation, using radioimmunoassay. Urocortin was detectable in maternal plasma from 7 weeks of gestation and concentrations did not change as gestation progressed. IR-urocortin in the maternal plasma eluted from a Sephadex G-50 column at the same site as synthetic urocortin and had a calculated retention coefficient (Kd) of 0.44. In summary, this study indicates that urocortin is produced by the decidua during human pregnancy and is detectable in maternal plasma. These data are consistent with the hypothesis that urocortin is produced locally by the decidua and may act to regulate uteroplacental blood flow.

Amnion↗

PubMed2000

Prostaglandin E(2) enhances chemical and mechanical sensitivities of pulmonary C fibers in the rat.

It has been recently reported that pulmonary reflex responses to injection or inhalation challenge of capsaicin are enhanced by exogenous Prostaglandin E(2) (PGE(2)). The present study was carried out to determine whether PGE(2) enhances the stimulatory effects of chemical stimulants and lung inflation on vagal pulmonary C fibers, and if so, whether the excitabilities of other types of lung afferents are also augmented by PGE(2). In anesthetized, open-chest rats, administration of PGE(2) (1.5 microgram/kg/min for 2 min) did not significantly change the baseline activity of vagal pulmonary C fibers, but it markedly enhanced the stimulatory effects of both low (0.25 microgram/kg) and high doses (0.5 microgram/kg) of capsaicin on these fibers. Similarly, potentiating effects of PGE(2) were found on the pulmonary C-fiber responses to injections of lactic acid and adenosine, although considerable variability existed in the degrees of potentiation between the different stimulants. Furthermore, PGE(2) infusion also significantly enhanced the C-fiber response to constant-pressure lung inflation (tracheal pressure [Pt] = 30 cm H(2)O). In contrast, PGE(2) did not alter the responses of either slowly adapting pulmonary receptors or rapidly adapting pulmonary receptors to lung inflation. In summary, these results show that the sensitivity of pulmonary C-fiber afferents to both mechanical and chemical stimuli is enhanced by PGE(2), suggesting that endogenous release of this autocoid may play a part in the airway irritation and dyspneic sensation associated with airway inflammation.

Animals↗

PubMed2000

Redundant regulation of meristem identity and plant architecture by FRUITFULL, APETALA1 and CAULIFLOWER.

The transition from vegetative to reproductive phases during Arabidopsis development is the result of a complex interaction of environmental and endogenous factors. One of the key regulators of this transition is LEAFY (LFY), whose threshold levels of activity are proposed to mediate the initiation of flowers. The closely related APETALA1 (AP1) and CAULIFLOWER (CAL) meristem identity genes are also important for flower initiation, in part because of their roles in upregulating LFY expression. We have found that mutations in the FRUITFULL (FUL) MADS-box gene, when combined with mutations in AP1 and CAL, lead to a dramatic non-flowering phenotype in which plants continuously elaborate leafy shoots in place of flowers. We demonstrate that this phenotype is caused both by the lack of LFY upregulation and by the ectopic expression of the TERMINAL FLOWER1 (TFL1) gene. Our results suggest that the FUL, AP1 and CAL genes act redundantly to control inflorescence architecture by affecting the domains of LFY and TFL1 expression as well as the relative levels of their activities.

Arabidopsis↗

PubMed2000

An analysis of two polymorphic points of the 7th intron of human p53 gene.

OBJECTIVE: To detect polymorphic points of the 7th intron of human p53 oncogene. METHODS: Polymerase chain reaction (PCR) and double- strand DNA direct sequencing were used to analyse sequence alteration of p53 intron 7. One hundred and five cases of normal human peripheral blood samples with no genetic relation were investigated. RESULTS: There were two polymorphic points in the 7th intron of p53 gene. The first one was localized at 73 base pair (bp) to 3'-end of exon 7; the other one at 93. Three genotypes were found. Twenty-two cases were of type TG, 37 cases were of type CT, and the other 46 cases were of heterozygote. Because the first point was alteration of GGGCCC to GGGTCC or its heterozygote, it had a point alteration of enzyme Apa I. CONCLUSION: There are two polymorphic points in the 7th intron of human p53 gene, which may be of importance to identification of individual genetic relation and to judging of a case in forensic medicine.

Genes, p53↗

PubMed2000

Intermediate and late rheumatoid arthritis treated by tonifying the kidney, resolving phlegm and removing blood stasis.

Eighty-seven cases of intermediate and late rheumatoid arthritis were treated with Instant Shu Guan Wen Jing Granules ([symbol: see text] Relaxing Joints by Warming Channels) and Instant Shu Guan Qing Luo Granules ([symbol: see text] Relaxing Joints by Removing Heat from the Lung Channel) to tonify the kidney, resolve phlegm and remove blood stasis, and compared with 41 cases treated with Instant Wang Bi Granules ([symbol: see text] Prescription for Arthralgia-syndrome). The treatment produced a clinical cure rate of 54.0% and a total effective rate of 90.8% as in against 29.3% and 73.2% respectively in the control group. The difference was significant (P < 0.01). Improvement in main symptoms and laboratory findings in the treatment group was all more marked than that in the control group (P < 0.05 or P < 0.01), with no side effects observed.

Adult↗

PubMed2000

[The effect of coxsackie virus B3 on intracellular calcium homeostasis in rat cardiomyocytes].

OBJECTIVE: To investigate the effect of coxsackievirus B3 (CVB3) on intracellular calcium, L type voltage dependent calcium channel (VDCC) and Na+/Ca2+ exchange (NCE) in adult rat cardiomyocytes. METHODS: Rat hearts were perfused with collagenase to gain single cardiomyocyte. The intracellular free calcium concentration of the cardiomyocytes were detected by laser confocal microscopy with calcium indicator, Fluo3-acetoxymethyl ester; and the currents of VDCC, Na+ and NCE were recorded by patch clamp techniques. RESULTS: The free intracellular calcium concentration increased from (51 +/- 43) nmo1/L in normal cardiomyocytes to (339 +/- 208) nmo1/L in CVB3 infected cardiomyocytes. The VDCC current increased from (4.13 +/- 0.75) pA/pF to (4.9 +/- 1.4) pA/pF after CVB3 infection, and the inward NEC current decreased from (-0.46 +/- 0.21) pA/pF to (-0.28 +/- 0.16) pA/pF; besides, the reverse potential of NCE was shifted from (29.4 +/- 7.0) mV to (41 +/- 14) mV with CVB3 infection. CONCLUSIONS: The increase of L type VDCC current and decrease of inward NCE current with shift of NCE reverse potential may partly attribute to intracellular free calcium accumulation; also, it may be the cause of cell damage and the occurrence of abnormal electric activities induced by CVB3 infection.

Animals↗

PubMed2000

[The regulation of calcium in the movement of colonic smooth muscle in wrap restraint stress rats].

OBJECTIVE: To investigate the influence of contraction of isolated colonic smooth muscle and role of guanylin in colonic movement in wrap restraint stress rats. METHODS: By using wrap restraint stress induced defecation rats, the tone of isolated longitudinal and circular colonic muscle strips and guanylin contents in colon and blood were measured by transducer and radioligand binding assay respectively. RESULTS: There were similarities between the intestinal effects of wrap restraint stress in rats and irritable bowel syndrome (IBS) in human. Therefore, wrap restraint stress rat is an appropriate animal model to study stress related intestinal dysfunction. In wrap restraint stress rats, both the tone of smooth muscle and the reaction to K(+), Ca(2+) and acetycholine increased significantly; meanwhile guanylin contents in blood and colon increased also. Trimebutine can decrease the basic tone of smooth muscle and reaction to Ca(2+), K(+) and acetycholine. CONCLUSIONS: The abnormality of colonic smooth muscle contraction is one of the mechanisms in IBS and regulation of colonic smooth muscle contraction is a new method to treat IBS.

Acetylcholine↗

PubMed2000

[Experimental and clinical study of gentamicin-loaded chitosan drug delivery system].

OBJECTIVE: To conduct a clinical study and release test for a drug delivery system (DDS) of gentamicin-loaded chitosan bar in attempt to extend its clinical application. METHODS: The diffusion behavior of gentamicin from chitosan DDS was detected using in vitro, in vivo release test. Eighteen cases of chronic osteomyelitis were treated by chitosan DDS. The clinical result was evaluated by wound healing and clinical and X-radiographic manifestation. RESULTS: Concentration of gentamicin about 926.7 microg/bar/day was released from DDS within the first 24 hours by in vitro diffusion test. It fell and sustained by 25th day with rate of 4.0 microg x bar(-1) x day(-1). In in vivo study, serum gentamicin concentration reached its peak level (0.92 microg/ml) 24 hours after implantation. No increase was observed in the concentration of BUN and Cr. In all bone tissue around the bar, 8 weeks after oderation the gentamicin concentration exceeded the minimum inhibitory concentration for the common causative organisms of osteomyelitis. The follow up time was 24.8 months (6 - 34). The initial cure ratio was 2/18 and the recurrence ratio zero. CONCLUSION: The gentamicin-loaded chitosan bar is a good DDS with sustained antibiotic effect in vivo and in vitro. It is an effective method for the treatment of bone infection.

Animals↗

PubMed2000

[Formation of stereocomplexes in atactic poly(methyl methacrylate) studied by FTIR].

The stereocomplexation of atactic poly(methyl methacrylate) (a-PMMA) films after isolated from acetone, benzene, and chloroform solution, respectively, was studied by Fourier transformation infrared (FTIR). The results of spectra showed that the stereocomplex was formed for the films cast from acetone and benzene solutions with the appearance of the characteristic bands for the stereocomplex. The population of trans-trans conformers for the i- and s-sequences increased and the side chain preferred to its energetically optimized conformation during the formation of stereocomplex. The stereocomplexes may be formed by the interactions between the i- and s-sequences in the same molecular chain. During the annealing process the self-aggregation of s-sequences played a role in the aggregation process of stereocomplex, which was a function of annealing temperature and annealing time.

Bone Cements↗

PubMed1999

Distribution and function of the adhesion molecule BEN during rat development.

It is well established that the notochord influences the development of adjacent neural and mesodermal tissue. Involvement of the notochord in the differentiation of the dorsal pancreas has been demonstrated. However, our knowledge of the signals involved in pancreatic development is still incomplete. In order to identify proteins potentially implicated during pancreatic differentiation, we raised and characterized monoclonal antibodies against previously established embryonic pancreatic ductal epithelial cell lines (BUD and RED). Using the MAb 2117, the cell surface antigen 2117 (Ag 2117) was cloned. The predicted sequence for Ag 2117 is the rat homologue of BEN. Initially reported as a protein expressed on epithelial cells of the chicken bursa of Fabricius, BEN is expressed in a variety of tissues during development and described as a marker for the developing central and peripheral chicken nervous systems. A role has been suggested for BEN in the adhesion of stem cells and progenitor cells to the blood-forming tissue microenvironment. In this study, we demonstrate that BEN, initially expressed exclusively in the notochord during the early development of rat, is implicated in pancreatic development. We show that Ag 2117 regulates the pancreatic epithelial cell growth through the ras and Jun kinase pathways. In addition, we demonstrate that Ag 2117 is able to regulate the expression of the transcription factor PDX1, required for insulin gene expression, in embryonic pancreas organ cultures.

Activated-Leukocyte Cell Adhesion Molecule↗

PubMed1999

FGF-19, a novel fibroblast growth factor with unique specificity for FGFR4.

We have identified a novel fibroblast growth factor, FGF-19, the most distant member of the FGF family described to date. FGF-19 is a high affinity, heparin dependent ligand for FGFR4 and is the first member of the FGF family to show exclusive binding to FGFR4. Human FGF-19 maps to chromosome 11 q13.1, a region associated with an osteoporosis-pseudoglioma syndrome of skeletal and retinal defects. FGF-19 message is expressed in several tissues including fetal cartilage, skin, and retina, as well as adult gall bladder and is overexpressed in a colon adenocarcinoma cell line.

Adenocarcinoma↗