Biomedical subjects

Q Liu

Publications and source records attributed to Q Liu.

At least 199 records · Page 11Linked to original sources

PubMed2000

IL-13-mediated worm expulsion is B7 independent and IFN-gamma sensitive.

B7 costimulation is a required component of many type 2 immune responses, including allergy and protective immunity to many nematode parasites. This response includes elevations in Th2 cytokines and associated effector functions including elevations in serum IgG1 and IgE and parasite expulsion. In studies of mice infected with Trichuris muris, blocking B7 ligand interactions inhibited protective immunity, suppressed IL-4 production, and enhanced IFN-gamma production, but unexpectedly did not inhibit production of the Th2 cytokine, IL-13. Blocking both IFN-gamma and B7 restored protective immunity, which was IL-13 dependent, but did not restore IL-4 or associated IgE responses. Although IL-13 was required for worm expulsion in mice in which both IFN-gamma and B7 were blocked, IL-4 could mediate expulsion in the absence of both IL-13 and IFN-gamma. These studies demonstrate that 1) B7 costimulation is required to induce IL-4, but not IL-13 responses; 2) IL-13 is elevated in association with the IFN-gamma response that occurs following inhibition of B7 interactions, but can only mediate IL-4-independent protection when IFN-gamma is also inhibited; and 3) increased IL-13 production, in the absence of increased IL-4 production, is not associated with an IgE response, even in the absence of IFN-gamma.

Abatacept↗

PubMed2000

Identification of a urokinase receptor-integrin interaction site. Promiscuous regulator of integrin function.

Adhesion and signaling by integrins require their dynamic association with nonintegrin membrane proteins. One such protein, the glycolipid-anchored urokinase receptor (uPAR), associates with and modifies the function of the beta(2)-integrin Mac-1 (CD11b/CD18). In this study, a critical non-I-domain binding site for uPAR on CD11b (M25; residues 424-440) is identified by homology with a phage display peptide known to bind uPAR. Recombinant soluble uPAR and cells expressing uPAR bound to immobilized M25, binding being promoted by urokinase and blocked by soluble M25, but not a scrambled control or homologous peptides from other beta(2)-associated alpha-chains. Mac-1, but not a mutated Mac-1 in which M25 was replaced with the homologous sequence of CD11c, co-precipitated with uPAR. In the beta-propeller model of alpha-chain folding, M25 spans an exposed loop on the ligand-binding, upper surface of alphaM, identifying uPAR as an atypical alphaM ligand. Although not blocking ligand binding to Mac-1, M25 (25-100 microM) inhibited leukocyte adhesion to fibrinogen, vitronectin, and cytokine-stimulated endothelial cells. M25 also blocked the association of uPAR with beta(1)-integrins and impaired beta(1)-integrin-dependent spreading and migration of human vascular smooth muscle cells on fibronectin and collagen. These observations indicate that uPAR associates with integrins directly and that disruption of this association broadly impairs integrin function, suggesting a novel strategy for regulation of integrins in the settings of inflammation and tumor progression.

Amino Acid Sequence↗

PubMed2000

[Prognostic effect of angina before acute myocardial infarction in elderly patients].

OBJECTIVE: The present study examined whether angina 48 h before acute myocardial infarction provided protection in early and adult patients. To investigate the effect of ischemic preconditioning in senescent heart. METHODS: We retrospectively verified whether antecedent angina within 48 h myocardial infarction exerted a beneficial effect on in-hospital outcomes in adult(< 60 years old, n = 68) and elderly (> or = 60 years old, n = 118) patients. RESULTS: In-hospital congestive heart failure was more frequent in adult patients without than in those with previous angina(16.7% vs 2.6%, P < 0.05), as were cardiogenic shock and death(23.3% vs 5. 3%, P < 0.05) and the combined end points(in-hospital congestive heart failure and shock or death) (40.0% vs 7.9%, P < 0.01). In contrast, the presence or absence of previous angina before acute myocardial infarction in elderly patients seemed to have no obvious influence, the incidence of in-hospital congestive heart failure(17.7% vs 20.0%, P > 0.05), shock and death(23.5% vs 20.3%, P > 0.05) and combined end points(41.2% vs 40.0%, P > 0.05). But the elderly patients with angina showed a significantly smaller infarct size compared with elderly patients without angina, the long-term cardiogenic death was more frequent in elderly patients without than in those with previous angina(18.0% vs 5.9%, P < 0.05). CONCLUSIONS: The presence of angina before acute myocardial infarction seems to confer significant protection against in-hospital outcomes in adults; this effect seems to be present in elderly patients. This study suggests that the protection afforded by angina in adult and elderly patients may involve the occurrence of ischemic preconditioning.

Aged↗

PubMed2000

Discrete mobility of single-stranded DNA in non-denaturing gel electrophoresis.

Gel electrophoresis is the standard method to separate, identify and purify nucleic acids. SSCP detects single base changes by altered mobility of single-stranded segments electrophoresed through non-denaturing polyacrylamide gels. Herein, changes in electrophoretic mobilities due to single base substitutions were measured for single-stranded segments of lengths ranging from 333 to 547 nt. A 484 nt segment in exon H of the human factor IX gene was studied most intensively. After SSCP, mobilities were determined by scanning autoradiograms at very high resolution (1200 d.p.i.), which allowed precise measurement of mobilities. When the mobilities of 46 single base substitutions were characterized, the distribution of mutant segments relative to a wild-type control was found to be discrete, i.e. the observed mobility values occurred in distinct ranges. Discrete mobility distributions were seen at different electrophoretic temperatures, buffer concentrations, segment lengths and segment sequences. In addition: (i) single base substitutions caused discontinuous distributions between highly dispersed and sharp bands; (ii) at least one single-stranded segment produced two sharp bands of similar intensity. These observations suggest that: (i) the single base changes in DNA segments in the size range 333-547 nt result in discrete conformational changes; (ii) individual DNA molecules of the same DNA segment can occasionally adopt two or more discrete conformations.

DNA, Single-Stranded↗

PubMed2000

A germ-line p53 mutation accelerates pulmonary tumorigenesis: p53-independent efficacy of chemopreventive agents green tea or dexamethasone/myo-inositol and chemotherapeutic agents taxol or adriamycin.

Recent evidence indicates that individuals with a p53 germ-line mutation (Li-Fraumeni syndrome) have a 50% risk of developing lung cancer by age 60. In this study, p53 heterozygous knockout mice and p53 transgenic mice carrying a dominant negative mutant were crossed with the A/J mouse, which is highly susceptible to lung tumor induction, to investigate whether a p53 germ-line mutation is a predisposing gene for carcinogen-induced pulmonary adenomas in mice. The number of lung tumors was not significantly increased in (TSG-p53 x A/J)F1 p53 heterozygous knockout mice as compared with that in (TSG-p53 x A/J)F1 wt mice 16 weeks after exposure to N-nitrosomethylurea (MNU). In contrast, an average of 22 lung tumors were observed in (UL53-3 x A/J)F1 mice carrying a mutant p53 transgene (135Valp53) compared with an average of 7 lung tumors seen in (UL53-3 x A/J)F1 wt mice after treatment with N-nitrosomethylurea. Similar enhancement of lung tumor multiplicity (approximately 3-fold) was seen when mutant versus wt mice were treated with the tobacco-related carcinogens benzo[a]pyrene or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. These results suggest that the mutant p53 transgene may have a dominant negative effect on the wt p53. The potential usefulness of this new mouse model in lung cancer chemoprevention and chemotherapy was examined. The chemopreventive efficacy of the green tea or a combination of dietary dexamethasone and myoinositol and the chemotherapeutic efficacy of Taxol or Adriamycin was examined in wt mice or mice with a mutation in the p53 gene. Mice treated with dexamethasone/myo-inositol and green tea displayed an average of 70 and 50% inhibition of lung tumors, respectively, regardless of p53 status. Similarly, when mice bearing established lung adenomas were treated with Taxol or Adriamycin, a decrease in tumor volume of approximately 70% was observed independent of p53 mutation status. Thus, the (UL53-3 x A/J)F1 p53 transgenic mouse seems to be an excellent model for human carriers of p53 germ-line mutations (Li-Fraumeni syndrome). Furthermore, the lung adenomas generated in this model possess mutations in both the K-ras proto-oncogene and the p53 tumor suppressor gene. This model should prove directly useful for chemoprevention and chemotherapy studies.

Alleles↗

PubMed2000

The SH2 inositol 5-phosphatase Ship1 is recruited in an SH2-dependent manner to the erythropoietin receptor.

Ship1 (SH2 inositol 5-phosphatase 1) has been shown to be a target of tyrosine phosphorylation downstream of cytokine and immunoregulatory receptors. In addition to its catalytic activity on phosphatidylinositol substrates, it can serve as an adaptor protein in binding Shc and Grb2. Erythropoietin (EPO), the primary regulator of erythropoiesis, has been shown to activate the tyrosine phosphorylation of Shc, resulting in recruitment of Grb2. However, the mechanism by which the erythropoietin receptor (EPO-R) recruits Shc remains unknown. EPO activates the tyrosine phosphorylation of Ship1, resulting in the interdependent recruitment of Shc and Grb2. Ship1 is recruited to the EPO-R in an SH2-dependent manner. Utilizing a panel of EPO-R deletion and tyrosine mutants, we have discovered remarkable redundancy in Ship1 recruitment. EPO-R Tyr(401) appears to be a major site of Ship1 binding; however, Tyr(429) and Tyr(431) can also serve to recruit Ship1. In addition, we have shown that EPO stimulates the formation of a ternary complex consisting of Ship1, Shc, and Grb2. Ship1 may modulate several discrete signal transduction pathways. EPO-dependent activation of ERK1/2 and protein kinase B (PKB)/Akt was examined utilizing a panel of EPO-R deletion mutants. Activation of ERK1/2 was observed in EPO-RDelta99, which retains only the most proximal tyrosine, Tyr(343). In contrast, EPO-dependent PKB activation was observed in EPO-RDelta43, but not in EPO-RDelta99. It appears that EPO-dependent PKB activation is downstream of a region that indirectly couples to phosphatidylinositol 3-kinase.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Overexpression of M68/DcR3 in human gastrointestinal tract tumors independent of gene amplification and its location in a four-gene cluster.

Fas-mediated apoptosis is an important regulator of cell survival, and abnormalities in this system have been shown to result in a number of human pathological conditions. A secreted member of the tumor necrosis factor receptor superfamily, DcR3, was recently reported to be amplified in human lung and colon cancers as a negative regulator of Fas-mediated apoptosis. We identified this gene, which we call M68. M68 genomic DNA, mRNA, and protein levels were examined in a series of human gastrointestinal tract tumors. Using M68 immunohistochemistry and a scoring system similar to that used for HER-2/neu, we found that M68 protein was overexpressed in 30 of 68 (44%) human adenocarcinomas of the esophagus, stomach, colon, and rectum. Tumors examined by Northern blot revealed M68 mRNA highly elevated in a similar fraction of primary tumors from the same gastrointestinal tract regions, as well as in the colon adenocarcinoma cell lines SW480 and SW1116. Further, we found M68 protein to be overexpressed in a substantial number of tumors in which gene amplification could not be detected by fluorescence in situ hybridization or quantitative genomic PCR, suggesting that overexpression of M68 may precede amplification in tumors. Finally, we find that M68 lies within a four-gene cluster that includes a novel helicase-like gene (NHL) related to RAD3/ERCC2, a plasma membrane Ras-related GTPase and a member of the stathmin family, amplification or overexpression of which may also contribute to cell growth and tumor progression.

ADP-Ribosylation Factors↗

PubMed2000

Identification of the Xenopus laevis homolog of Saccharomyces cerevisiae DNA2 and its role in DNA replication.

The DNA2 gene of Saccharomyces cerevisiae is essential for growth and appears to be required for a late stage of chromosomal DNA replication. S. cerevisiae Dna2p (ScDna2p) is a DNA helicase and also a nuclease. We have cloned and sequenced the homologous gene from Xenopus (Xenopus Dna2). Xenopus Dna2p (XDna2p) is 32% identical to ScDna2p, and the similarity extends over the entire length, including but not limited to the five conserved helicase motifs. XDna2p is even more closely related (60% identical) to a partial human cDNA. The Xenopus Dna2 (XDna2) gene was able to complement an S. cerevisiae dna2-1 mutant strain for growth at the nonpermissive temperature, suggesting that XDna2p is a functional as well as a structural homolog of the yeast protein. Recombinant XDna2p was expressed in insect cells and purified. Like the ScDna2p purified from yeast, it is a single-stranded DNA endonuclease and a DNA-dependent ATPase, suggesting that both of these activities are part of the essential function of Dna2p. However, unlike ScDna2p from yeast, recombinant XDna2p showed no DNA helicase activity. When XDna2 was immunodepleted from interphase egg extracts, chromosomal DNA replication was almost completely inhibited. From the size of the residually synthesized DNA from the XDna2-depleted egg extracts, it seems that initiation of DNA replication may be impaired. This interpretation is also supported by the normal DNA replication of M13 single-stranded DNA in the XDna2-depleted egg extracts.

Amino Acid Sequence↗

PubMed2000

DNA computing on surfaces.

DNA computing was proposed as a means of solving a class of intractable computational problems in which the computing time can grow exponentially with problem size (the 'NP-complete' or non-deterministic polynomial time complete problems). The principle of the technique has been demonstrated experimentally for a simple example of the hamiltonian path problem (in this case, finding an airline flight path between several cities, such that each city is visited only once). DNA computational approaches to the solution of other problems have also been investigated. One technique involves the immobilization and manipulation of combinatorial mixtures of DNA on a support. A set of DNA molecules encoding all candidate solutions to the computational problem of interest is synthesized and attached to the surface. Successive cycles of hybridization operations and exonuclease digestion are used to identify and eliminate those members of the set that are not solutions. Upon completion of all the multistep cycles, the solution to the computational problem is identified using a polymerase chain reaction to amplify the remaining molecules, which are then hybridized to an addressed array. The advantages of this approach are its scalability and potential to be automated (the use of solid-phase formats simplifies the complex repetitive chemical processes, as has been demonstrated in DNA and protein synthesis). Here we report the use of this method to solve a NP-complete problem. We consider a small example of the satisfiability problem (SAT), in which the values of a set of boolean variables satisfying certain logical constraints are determined.

Computing Methodologies↗

PubMed2000

Cysteine scanning mutagenesis of the noncatalytic nucleotide binding site of the yeast V-ATPase.

To investigate residues involved in the formation of the noncatalytic nucleotide binding sites of the vacuolar proton-translocating adenosine triphosphatase (V-ATPase), cysteine scanning mutagenesis of the VMA2 gene that encodes the B subunit in yeast was performed. Replacement of the single endogenous cysteine residue at position 188 gave rise to a Cys-less form of the B subunit (Vma2p) which had near wild-type levels of activity and which was used in the construction of 16 single cysteine-containing mutants. The ability of adenine nucleotides to prevent reaction of the introduced cysteine residues with the sulfhydryl reagent 3-(N-maleimidopropionyl)biocytin (biotin-maleimide) was evaluated by Western blot. Biotin-maleimide labeling of the purified V-ATPase from the wild-type and the mutants S152C, L178C, N181C, A184C, and T279C was reduced after reaction with the nucleotide analog 3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate (BzATP). These results suggest the proximity of these residues to the nucleotide binding site on the B subunit. In addition, we have examined the level of endogenous nucleotide bound to the wild-type V-ATPase and to a mutant (the A subunit mutant R483Q) which is postulated to be altered at the noncatalytic site and which displays a marked nonlinearity in ATP hydrolysis (MacLeod, K. J., Vasilyeva, E., Baleja, J. D., and Forgac, M. (1998) J. Biol. Chem. 273, 150-156). The R483Q mutant contained 2.6 mol of ATP/mol of V-ATPase compared with the wild-type enzyme, which contained 0.8 mol of ATP/mol of V-ATPase. These results suggest that binding of additional ATP to the noncatalytic sites may modulate the catalytic activity of the enzyme.

Adenine Nucleotides↗

PubMed2000

Developmental expression of insulin receptor substrate-2 during dimethylsulfoxide-induced differentiation of human HL-60 cells.

Insulin receptor substrate-2 (IRS-2) is phosphorylated on tyrosine by a number of cytokine receptors and is implicated in the activation of phosphatidylinositol 3'-kinase (PI3-kinase). Here, we demonstrate that induction of granulocytic differentiation of human promyeloid HL-60 cells leads to an increase in the amount of IRS-2 that is phosphorylated in response to insulin-like growth factor (IGF)-I. Although PI3-kinase is often activated following interaction with IRS-1, we could not detect IRS-1 protein, IRS-1 mRNA, or IRS-1-precipitable PI3-kinase enzymatic activity. However, PI3-kinase activity that was coimmunoprecipitated with either anti-phosphotyrosine or anti-IRS-2 following IGF-I stimulation was increased 100-fold. Heightened tyrosine phosphorylation of IRS-2 during granulocytic differentiation was not caused by an increase in expression of the tyrosine kinase IGF-I receptor, as measured by the amount of both the alpha- and beta-subunits. Instead, immunoblotting experiments with an Ab to IRS-2 revealed that induction of granulocytic differentiation caused a large increase in IRS-2, and this occurred in the absence of detectable IRS-1 protein. These IRS-2-positive cells could not differentiate into more mature myeloid cells in serum-free medium unless IGF-I was added. These data are consistent with a model of granulocytic differentiation that requires at least two signals, the first of which leads to an increase in the cytoplasmic pool of IRS-2 protein and a second molecule that acts to tyrosine phosphorylate IRS-2 and enhance granulocytic differentiation.

Cell Differentiation↗

PubMed2000

Effect of cytoreductive surgery on survival of patients with recurrent epithelial ovarian cancer.

BACKGROUND AND OBJECTIVES: The value of secondary cytoreductive surgery is still controversial, especially in patients with recurrent epithelial ovarian cancer. In this retrospective study, we investigated the effect on survival of secondary cytoreduction for recurrent disease and variables influencing redebulking surgical outcome. METHODS: Between 1986 and 1997, 60 patients who received primary cytoreductive surgery and platinum-based chemotherapy for stage III and IV epithelial ovarian cancer experienced disease recurrence at least 6 months after completion of primary therapy, and secondary surgical cytoreduction was performed. The optimal residual disease cutoff was 1.0 cm. The Cox proportional regression model and Logistic stepwise regression were used in statistical processing of the data. RESULTS: The median progression-free interval between the two operations was 13 months (range, 6-56 months). Optimal secondary cytoreduction was achieved in 23 patients (38.33%). There was a significant difference in survival between patients who were optimally cytoreduced compared to those suboptimally cytoreduced, with an estimated median survival in the optimal group of 19 months vs. 8 months in the suboptimal group (chi(2) = 22.04, P = 0.0000). Prognosis of survival for individuals with progression-free interval >12 months was better than that of those with the interval </=12 months (chi(2) = 5.22, P = 0.0224). Patients with ascites at disease recurrence suffered a pessimistic outcome, with an estimated median survival of 6 vs. 13 months in those without ascites (chi(2) = 13.99, P = 0.0002). Multivariate analysis strongly suggested that residual disease after second operation, ascites at disease recurrence, and progression-free interval were independent prognostic factors of survival. Logistic stepwise regression revealed that recurrent ascites (P = 0.0072, relative risk = 20.36) and residual disease after the second operation (P = 0.0096, relative risk = 5.16) were important determinants of secondary surgical outcome. CONCLUSIONS: Secondary cytoreductive surgery significantly lengthened survival for patients with recurrent epithelial ovarian cancer. Patients with ascites at disease recurrence, however, were not suitable for aggressive secondary surgery, and redebulking surgery for those with residual disease of >1.0 cm after primary operation should be considered prudently.

Adult↗

PubMed2000

The human factor IX gene as germline mutagen test: samples from Mainland China have the putatively endogenous pattern of mutation.

Germline mutations are the major source of genetic variation that allows a species to evolve over time but at the cost of Mendelian disease and genetic predisposition to multifactorial diseases. Previous analyses have revealed that the pattern of germline mutations in the factor IX gene (F9) is similar among a variety of ethnically and geographically diverse populations and compatible with the ancient pattern that has shaped the mammalian genome. Here, we compare the pattern of germline mutation in a population of hemophilia B patients from Mainland China (n=66) to that in U.S. Caucasians, Blacks, and Mexican Hispanics and stratify by disease severity and ethnicity. The similar pattern of germline mutation in all ethnic groups studied to date provides additional data compatible with the inference that endogenous processes predominate in germline mutations.

China↗

PubMed2000

Increased alpha2-adrenergic constriction of isolated arterioles in diffuse scleroderma.

OBJECTIVE: Vasospasm and ischemic organ injury are important in the pathogenesis of systemic sclerosis (SSc; scleroderma). The present study was performed to determine whether SSc arterioles have an intrinsic disturbance in vasoconstrictor activity. METHODS: Skin biopsy samples were obtained from the upper arm of 11 patients with diffuse SSc (clinically uninvolved skin) and 8 age- and sex-matched control subjects. Dermal arterioles were dissected from the biopsy sample and mounted in a myograph for continuous monitoring of arteriolar diameter. The resting internal diameter of control and SSc arterioles was similar (mean +/- SEM 164+/-15 micro and 166+/-18micro, respectively). RESULTS: Dermal arterioles displayed no spontaneous constrictor activity in the absence of stimulation. Vasoconstriction in response to KCI, a receptor-independent activator of smooth muscle, or to phenylephrine, a selective alpha1-adrenergic receptor (alpha1-AR) agonist, was similar in control and SSc arterioles. However, constrictor responses to UK 14,304, a selective alpha2-AR agonist, were increased in SSc compared with control arterioles (maximal constriction responses of 25+/-5% and 67+/-4% [mean +/- SEM] in control and SSc arterioles, respectively; P = 0.000014). Mechanical denudation of the endothelium did not alter reactivity to alpha2-AR activation, indicating that the enhanced constriction in SSc was not mediated by changes in endothelial dilator activity. Indeed, in arterioles constricted with phenylephrine, the endothelial stimuli acetylcholine or bradykinin evoked endothelium-dependent relaxation that was similar in control and SSc arterioles. CONCLUSIONS: Vascular smooth muscle in SSc arterioles displayed a selective increase in alpha2-AR reactivity. The endothelial dilator function appeared normal. Altered activity of smooth muscle alpha2-ARs may contribute to the vasospastic activity that is a prominent feature of the SSc disease process.

Adrenergic alpha-2 Receptor Agonists↗

PubMed2000

Potential Energy Curves of Some Electronic Excited States of Metal Diatomic Molecules Using the Energy Consistent Method.

An analytical five-term expansion potential is suggested to improve the recently proposed energy consistent method (ECM) potential based on a three-term expansion [Weiguo Sun, Mol. Phys. 92, 105 (1997) and Weiguo Sun and Hao Feng, J. Phys. B: At., Mol. Opt. Phys. 32, 5109 (1999)]. Applications of the new ECM to the electronic excited state 3(1)Pi of NaK, the excited state 2(3)Sigma(+)(g) of Na(2), and the excited states 3(1)Sigma(+)(u) and 3(1)Pi(u) of K(2) molecules show that the new ECM potential not only agrees excellently with the known Rydberg-Klein-Rees (RKR) data or accurate configuration interaction (CI) studies but also gives the potential data at the molecular asymptote and the dissociation region where experimental and quantum mechanical studies may have difficulties. The new ECM can correct the artifact which appeared in the three-term expansion potentials of both the previous ECM and the Huxley-Murrell-Sorbie (HMS) potential and can describe some states to which both the previous ECM and the HMS fail. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

Cloning and functional expression of rat eag2, a new member of the ether-à-go-go family of potassium channels and comparison of its distribution with that of eag1.

A second mammalian gene for the ether-à-go-go (eag) potassium channel has been cloned from the rat, and its predicted protein sequence is 70% identical to that of rat ether-à-go-go1 with a further 10% conservatively replaced residues. The rat eag2 mRNA was predominantly expressed in neural tissue and was not detected in adult skeletal, cardiac, or smooth muscle. Within the brain, its distribution overlaps that of rat ether-à-go-go1 in specific regions within the cortex and olfactory bulb, but was differentially distributed in other locations, being scanty within the cerebellum, and most notably present in the thalamus, inferior colliculus, and certain brainstem nuclei. Heterologous expression of rat eag2 in HEK-293 cells gave rise to a voltage-gated, noninactivating potassium current, active at the cells' resting potential and blocked by low nanomolar concentrations of cytosolic calcium. Thus, in neurones, this current is likely to impart a modulation in membrane conductance, which is sensitively responsive to resting internal calcium, and levels of electrical activity.

Animals↗

PubMed2000

Construction and identification of recombinant adenovirus vector containing the hVEGF165 gene.

To construct the recombinant adenovirus vector containing the cDNA for human vascular endothelial growth factor (hVEGF165), the cDNA for hVEGF165 was subcloned into pACCMV.pLpA. Subsequently, this recombinant pACCMV.hVEGF was co-transfected into 293 cells together with pJM17 to obtain the replication-deficient recombinant adenovirus containing hVEGF gene--AdCMV.hVEGF. The VEGF gene expression was detected by using RT-PCR and Western blot in rabbit aorta vascular smooth muscle cells (VSMC) infected with AdCMV.hVEGF. Cultured human umbilical vein endothelial cells (HUVEC) were incubated with the conditioned medium (CM) from above mentioned VSMC infected with AdCMV.hVEGF to observe the effect of VEGF on proliferation of HUVEC. 48 h after the infection with AdCMV.hVEGF, VSMC demonstrated VEGF expression, and the expressed VEGF could stimulate the proliferation of HUVEC in vitro. Successfully prepared AdCMV.hVEGF165 could express biologically active VEGF in infected VSMC, and stimulate proliferation of HUVEC.

Adenoviridae↗

PubMed2000

Preliminary study on the relationship between cAMP level and gsp expression in cultured human pituitary somatotrophinomas.

In order to investigate the relationship between abnormal intracellular signal transduction and tumorgenesis of human pituitary somatotrophinomas, the effects of protein kinase A (PKA)-dependent growth hormone (GH) releasing hormone (GHRH) and protein kinase C (PKC)-dependent GH-releasing peptide (GHRP-6) on cAMP production were observed by using cell culture and biochemical methods, and the expression of the gsp oncogene was detected by using PCR and direct sequence assay methods in 11 patients with human pituitary somatotrophinomas. It was found that GHRP-6 exerted significant stimulatory effect on cAMP production by 2 gsp-positive tumors and no effect on the gsp-negative tumors. GHRP-6 could enhance the stimulation of cAMP production induced by GHRH in tumor without gsp oncogenes. It was suggested that both GHRH and GHRP-6 exert identical effects on human pituitary soamtotrophinomas, which was contributed to the cross-talk between the two intracellular signal transduction pathways in pituitary cells.

Adenoma↗