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Q Liu

Publications and source records attributed to Q Liu.

At least 253 records · Page 14Linked to original sources
PubMed2000

Association of gastric epithelial apoptosis with the ability of Helicobacter pylori to induce a neutrophil oxidative burst.

Both polymorphonuclear cell infiltration and increased epithelial apoptosis are seen in gastric mucosa in the presence of Helicobacter pylori infection. This study examined the association between bacterial ability to stimulate an oxidative burst in neutrophils and epithelial apoptosis. Biopsy specimens were obtained from 15 patients to detect apoptotic cells by the TUNEL method. H. pylori strains isolated from corresponding stomach biopsy samples were tested for the ability to stimulate an oxidative burst in human neutrophils. Neutrophils were isolated from healthy subjects without H. pylori infection and the oxidative burst was measured by flow cytometry with dichlorofluorescein diacetate. Stimulation with H. pylori increased both the percentage of activated cells and fluorescence intensity. There was a significant positive correlation between the number of epithelial apoptotic cells and fluorescence intensity. Increased neutrophil oxidative burst stimulated by H. pylori may play a role in enhanced gastric mucosal DNA damage and consequent atrophic gastritis and gastric cancer.

Apoptosis↗
PubMed2000

Agnoprotein-1a of avian polyomavirus budgerigar fledgling disease virus: identification of phosphorylation sites and functional importance in the virus life-cycle.

The avian polyomavirus budgerigar fledgling disease virus (BFDV) encodes an unusual set of four agnoproteins in its late upstream region. Of the two pairs of these proteins, which overlap each other in two different reading frames, the p(L1)-promoted agnoprotein-1a (agno-1a) is the dominant species and is able to support virus propagation in the absence of the other three polypeptides. Viral BFDV agno-1a, and also agno-1a expressed via an influenza virus vector, consists of a complex series of electrophoretically separable subspecies that can be reduced by phosphatase action down to a primary unphosphorylated protein with an apparent molecular mass of 31 kDa. Through peptide mass spectrometry and site-directed mutagenesis, the positions of four serine and three threonine residues have been determined as phosphate-accepting groups, which are partially modified by the combined action of three different cellular kinases. Since extensively phosphorylated agno-1a is required for its intracellular function, control over VP protein expression, and unphosphorylated agno-1a is observed as an additional component in the BFDV virion, both extreme subspecies appear to be drawn from that complex mixture, which also includes the intermediate stages of phosphorylation.

Amino Acid Sequence↗
PubMed2000

Poly

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Journal Article↗
PubMed2000

Quantitative, competitive PCR analysis of porcine circovirus DNA in serum from pigs with postweaning multisystemic wasting syndrome.

A competitive PCR (cPCR) assay was developed for monitoring porcine circovirus (PCV) DNA in serum samples from piglets. The cPCR was based on competitive coamplification of a 502- or 506-bp region of the PCV type 1 (PCV1) or PCV2 ORF2, respectively, with a known concentration of competitor DNA, which produced a 761- or 765-bp fragment, respectively. The cPCR was validated by quantification of a known amount of PCV wild-type plasmids. We also used this technique to determine PCV genome copy numbers in infected cells. Furthermore, we measured PCV DNA loads in clinical samples. More than 50% of clinically healthy piglets could harbor both types of PCV. While PCV1 was detected in only 3 of 16 pigs with postweaning multisystemic wasting syndrome (PMWS), all the sick piglets contained PCV2. A comparison of the PCV2 DNA loads of healthy and sick animals revealed a significant difference, indicating that the development of PMWS may require a certain amount of PCV2.

Animals↗
PubMed2000

Chromosomal localization of GPR48, a novel glycoprotein hormone receptor like GPCR, in human and mouse with radiation hybrid and interspecific backcross mapping.

We report the chromosomal localization in both mouse and human of a novel G-protein-coupled receptor, GPR48, which resembles glycoprotein hormone receptors, that may be implicated in Wilms tumor deletion syndromes such as WAGR. This receptor forms a novel sub-family of glycoprotein hormone-like GPCRs. We have mapped this receptor to human chromosome 11p14-->p13 by several approaches, including radiation hybrid and interspecific backcross mapping, and show that GPR48 is close to BDNF. This data differs from the recently published mapping of LGR4 (5q34-->q35.1) (Hsu et al., 1998). Additionally, we show that Gpr48 and Bdnf are tightly linked on mouse chromosome 2, in a region with conserved synteny to human 11p14-->p13.

Animals↗
PubMed2000

In vivo and in vitro stability of modified poly(urethaneurea) blood sacs.

In the present study, we investigate the in vivo and in vitro stability of modified poly(urethaneurea) (BioSpan MS/0.4) blood sacs. Blood sacs were utilized primarily in left ventricular assist devices that were implanted in calves for times ranging from 5 to 160 days. Cyclic testing in vitro was also conducted on similar sacs. Various analytical methods were employed to characterize the sacs after in vivo or in vitro service and corresponding retained "control" sacs. These methods included ATR-FTIR spectroscopy, scanning electron microscopy and gel permeation chromatography. In general, the characteristics of implanted and in vitro cycled sacs were similar to their control sacs. Thermal and microtensile properties were unchanged after testing. The same was true for the ATR-FTIR spectra, indicating relative chemical stability for the time frames explored here. The only significant changes occurred in molecular weight and gross surface morphology. A modest increase in weight average molecular weight was observed for most implanted blood sacs, indicating some type of chain extension or branching reaction in vivo. Although the surface morphologies of implanted blood sacs were often similar to their control sacs, we sometimes observed limited pitting on the nonblood contacting surfaces in regions of the sac that experience maximum bending during service.

Animals↗
PubMed2000

Subcellular distribution of somatostatin sst2A receptors in human tumors of the nervous and neuroendocrine systems: membranous versus intracellular location.

The distribution of the sst2A receptor was investigated, using immunohistochemistry, with the specific antipeptide antibody R2-88, in a total of 120 tumors of the nervous and the neuroendocrine systems, including small-cell lung carcinomas, medulloblastomas, neuroblastomas, pheochromocytomas, and paragangliomas. The great majority of the tumor samples, frozen or formalin-fixed, showed a positive immunohistochemical staining with R2-88, and an excellent correlation with receptor autoradiography using 125I[Tyr3]-octreotide. Whereas small-cell lung carcinomas and medulloblastomas had a predominantly plasma membrane staining, pheochromocytomas and neuroblastomas had variable ratios of cell surface and intracellular staining. Strikingly, a preferentially cytoplasmic staining was seen in tumors with a high level of somatostatin gene expression, whereas a more plasma membranous staining was seen in tumors lacking somatostatin messenger RNA. Specificity of both the plasma membrane and the cytoplasmic staining pattern was confirmed in immunoblots, which showed the immunoreactive receptor migrating as a characteristic 70-kDa broad band. In both immunohistochemical and immunoblotting experiments, staining was abolished by antibody blockade with 100 nM antigen peptide. These results describe, for the first time, the localization of the sst2A receptor protein in human small-cell lung carcinomas, medulloblastomas, neuroblastomas, and paragangliomas. Moreover, it is the first report investigating possible causes for distinct subcellular localizations of sst2A in human tissues. We show that the subcellular distribution of the receptor may be dependent on the surrounding somatostatin concentration, consistent with both the known effect of somatostatin to cause sst2A receptor internalization and an autocrine regulation of tumors by the peptide they produce. Moreover, our demonstration that the sst2A receptor can be identified in this group of tumors using simple immunohistochemical methods in formalin-fixed, paraffin-embedded material opens numerous diagnostic, therapeutic, and prognostic opportunities.

Autoradiography↗
PubMed2000

Dose-effect relationship of dicentric and ring chromosomes in lymphocytes of individuals living in the high background radiation areas in China.

Chromosomes of 39 healthy family members (3 generations from 13 families) living both in the high-level background radiation areas (HBRA) and the control areas (CA) were studied. Cumulative dose from birth to the time of blood sampling was estimated by calculating measured exposure rate in each individual. The cumulative doses ranged 30.9-358.9 and 6.0-59.2 mGy for HBRA and CA, respectively. Peripheral lymphocyte chromosome preparations were made according to our improved method. Dicentric and ring chromosomes (Dic + Rc) were scored in average 2,527 cells per individual in HBRA and 2,694 cells in CA under a microscope equipped with an automated stage. A positive correlation between Dic + Rc and age was found in HBRA, while no such dose relationship was clear in CA. The frequency of Dic + Rc linearly increases over lifetime due to chronic low dose exposure and it is likely that the activation of repair enzymes is not triggered in the present HBRA. Threshold dose (rate) of the induction of chromosome aberrations, if any, is below the present dose (rate) level.

Adult↗
PubMed2000

Analysis of ovariectomy and estrogen effects on body composition in rats by X-ray and magnetic resonance imaging techniques.

Resistance of bone to fracture--bone strength--has been shown to depend on both the amount of bone and its architectural spatial organization. In vivo magnetic resonance (MR) techniques have the capability of imaging bone tissue, including the trabecular microarchitecture and the marrow composition. We have applied in vivo and ex vivo MR methods to the tibia in an ovariectomized rat model of osteoporosis. Specifically, in vivo high-resolution three-dimensional MR imaging and localized MRS were facilitated by specialized coils and high field magnets, resulting in enhanced sensitivity of detection. As a result, in vivo and ex vivo differences in marrow composition were found between sham-ovariectomized, ovariectomized, and ovariectomized animals treated with 17-beta-estradiol. Estrogen effects were detected in vivo 7 days after surgery (3 days into treatment) as a decrease in the tibial fat signal level. The in vivo effects of ovariectomy were observed 56 days after surgery as an increase in MR image fat signal level and spectral fat/water ratio in the proximal tibia. Ex vivo measurements of tibial marrow water signal discriminated clearly between the sham and ovariectomized groups and showed increased individual variations in the treatment group. Imaging further showed that the highest fat content is observed in the epiphysis. Computed tomography confirmed ovariectomy-induced loss of bone in the proximal tibial metaphysis compared with the sham group. This loss of cancellous bone with ovariectomy is consistent with the MR observations of increases in both fat and water in the metaphysis. These data showed that MR techniques complement X-ray techniques in the bone, water, and fat compositional analysis of the appendicular skeleton in response to ovariectomy and pharmacological treatment.

Adipose Tissue↗
PubMed2000

The effect of interleukin-6 on bacterial translocation in acute canine pancreatitis.

BACKGROUND: Bacterial translocation from the gut to mesenteric lymph nodes and other extraintestinal sites is an important source of infection in acute pancreatitis. Impaired host immunity is known to promote bacterial translocation. Interleukin-6 (IL-6) is a multifunctional cytokine that regulates the immune response, acute phase reaction, and hematopoiesis. METHODS: Twenty-four mongrel dogs (18-29 kg) were studied in four equal groups. In Groups I and II, acute pancreatitis was induced by direct pressure injection of 4% taurocholate and trypsin into the pancreatic duct at laparotomy. Groups III and IV had only laparotomy. Group I and III dogs were given IL-6 (50 microg/kg/d, sq) daily starting 24 h after operation and Group II and IV dogs received an equal volume of saline administered at similar time. All animals had blood drawn for culture, complete blood count (CBC), platelets, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and amylase on d 0, 1, 4, and 7. On d 7, mesenteric lymph nodes (MLN), spleen, liver, pancreas, and cecum were harvested for pathology study and for cultures of aerobic and anaerobic bacteria. Quantitative cecal cultures of aerobic and anaerobic bacteria were obtained. RESULTS: All Group I and Group II dogs had severe pancreatitis. The increase of plasma CRP in Group I was sustained throughout treatment (1.3+/-0.3 on d 0 vs 3.1+/-0.3*, 3.0+/-0.3*, and 2.9+/-0.3* on d 1,4, and 7, respectively). Plasma CRP was increased in Group II on d 1 and d 4 (1.3+/-0.3 mg/dL on d 0 vs 3.6+/-0.3* mg/dL on d 1, and 3.1+/-0.3* on d 4, *p < 0.05). There were no differences in white blood cell (WBC) count, differential, platelets, and ESR between Groups I and II. Bacterial translocation to MLN was lower in Group I (1/6) than in Group II (6/6) (p < 0.05). All 6 dogs in Group II had bacterial spread to distant sites compared to 2 of 6 dogs in Group I (p = 0.066). Both MLN and other distant organ cultures were negative in Group III and only 1 of 6 MLN cultures was positive in Group IV. CONCLUSIONS: IL-6 treatment decreases bacterial translocation to MLN and may be beneficial in reducing septic complications in acute pancreatitis.

Acute Disease↗
PubMed2000

Scanning by DOVAM-S detects all unique sequence changes in blinded analyses: evidence that the scanning conditions are generic.

The [detection of virtually all mutations]-SSCP (DOVAM-S) is a highly sensitive variant of single strand conformation polymorphism (SSCP). Mutations in the factor IX gene were used to find a set of five SSCP conditions that detects virtually all mutations. A blinded analysis of the factor IX gene in patients with hemophilia B detected 82 of 82 unique mutations. Since the method was developed and tested on the factor IX gene, it is possible that the conditions selected work more efficiently in the factor IX gene than in other genes. To test the general applicability of the conditions under which DOVAM-S detected all mutations in this gene, blinded analyses were performed in the human factor VIII and ataxia-telangiectasia (ATM) genes. Segments were amplified individually, combined into groups of 16 to 18 amplified segments and electrophoresed in five different nondenaturing conditions of varying matrices, buffers, temperatures and additives. Blinded analyses were performed in 92 samples from patients with hemophilia A (factor VIII gene) and 19 samples from A-T patients (ATM gene). Combined with an earlier blinded analysis in the factor IX gene, all of the 250 mutations and polymorphisms (180 of which are unique) were detected in both analyses. For two, three and four joint conditions, the average detection frequency ranged from 77%-97%, 91%-100% and 95%-100%, respectively. For each of the genes, one mutation may have been missed if only four conditions were used. With DOVAM-S, approximately 500 kb of autosomal sequence can be scanned in five gels with virtually 100% detection of mutations within the scanned region. The detection of 180 out of 180 unique sequence changes implies that DOVAM-S detects at least 96.5% (P = 0.03) of mutations. Blinded analyses that detect 400 unique sequence changes are required to determine that a scanning method detects at least 98.5% of mutations.

Ataxia Telangiectasia↗
PubMed2000

Pyrophosphorolysis-activated polymerization (PAP): application to allele-specific amplification.

To measure mutation load or to detect minimal residual disease, a robust method for identifying one mutant allele in the range of 10(6)-10(9) wild-type alleles would be advantageous. Herein, we present evidence that pyrophosphorolysis-activated polymerization (PAP) has the potential to provide a highly specific and robust method of allele-specific amplification if DNA polymerases with higher pyrophosphorolysis activity can be found or engineered. In PAP, pyrophosphorolysis and polymerization by DNA polymerase are coupled serially by utilizing a pyrophosphorolysis-activatable oligonucleotide (P*). P*, which is an allele-specific oligonucleotide with a dideoxynucleotide at the 3' terminus, can be activated by pyrophosphorolysis to remove the 3' terminal dideoxynucleotide in the presence of pyrophosphate (PPi) and the complementary strand of the allelic template; then the activated P* can be extended by DNA polymerization. Specificity results from both pyrophosphorolysis and polymerization because significant nonspecific amplification requires the combination of mismatch pyrophosphorolysis and misincorporation by the DNA polymerase, which is an extremely rare event. Proof of principle has been achieved with a polymorphic site within the human D1 dopamine receptor gene. The effects of the dideoxyoligonucleotide sequences, DNA polymerases, PPi concentrations, allele-specific templates, pH and dNTP concentrations were examined.

Alleles↗
PubMed2000

Cloning and characterization of CIS 1b (cytokine inducible SH2-containing protein 1b), an alternative splicing form of CIS 1 gene.

JAK-STAT pathway is essential in relaying cytokine signals and plays a vital role in cellular responses such as proliferation, differentiation and immunity. Some members of a recently found cytokine-inducible SH2 protein (CIS, =SOCS or SSI) family have proved to have negative effects on modulating JAK-STAT signaling pathway. In the present study, a novel human cDNA (CIS1b) which proved to be a variant of CIS1 gene was isolated by screen human placenta lambda gt11 cDNA library and 5'-rapid amplification of cDNA ends (RACE). Furthermore, the gene structure of CIS1 was determined by comparing the cDNA sequences of CIS1 and CIS1b to the genomic sequence in human chromosome 3p21.3. The expression patterns of CIS1b as well as CIS1 were analysed by Northern blot.

Alternative Splicing↗
PubMed2000

Clinical application of 201Tl SPECT imaging of brain tumors.

UNLABELLED: This study investigated the clinical usefulness of evaluating the histologic grade of brain tumors by 201Tl SPECT brain imaging. METHODS: Early and delayed SPECT brain images were obtained about 10 min and 3 h, respectively, after intravenous injection of 111MBq (3 mCi) 201Tl in 9 healthy subjects (control subjects), 3 patients with brain hematomas, and 41 patients with brain tumors. Semiquantitative data were obtained for early and delayed 201Tl uptake indices and 201Tl retained index in all patients and healthy subjects. RESULTS: In 9 healthy subjects, there was little radioactivity in brain substance. In all patients with brain hematomas or tumors, a high tracer uptake was visible in lesions on early images, but the radioactivity in lesions varied with the histologic nature of the lesion on delayed images. The radioactivity decreased remarkably in brain hematomas (average retained index, 0.61 +/- 0.04). The radioactivity was stable or decreased slightly in benign or low-grade tumors (average retained index, 0.96 +/- 0.24). The radioactivity was increased in high-grade or metastatic tumors (average retained index, 1.26 +/- 0.28). CONCLUSION: This study indicates that 201Tl brain SPECT early and delayed imaging is very useful in brain tumor localization, in distinguishing low-grade from high-grade brain tumors, in predicting histologic grades of brain tumors, and in detecting residual or recurrence of brain tumors postoperatively. 201Tl brain SPECT may also offer the most accurate assessment of response to therapy.

Adult↗
PubMed2000

[Construction of prokaryotic expression vector of hALR and its expression in E.Coli].

OBJECTIVE: To construct prokaryotic expression vector of hALR and express rhALR in E.Coli. through PCR and recombinant gene technology. METHODS: The coding region with Nde I and BamH I sites of hALR was obtained from pUC19-hALR constructed with PCR method. PCR product and plasmid pET11a were digested by corresponding endonucleases, respectively. The fragments cut were ligated by T(4) DNA ligase to gain recombinant expression vector. The recombinant plasmid pET11a-hALR was electrotransformed into BL(21) (DE(3)) strain. The rhALR was expressed in the bacteria under induction of IPTG. RESULTS: Endonucleases digesting and DNA sequening confirmed that the coding region of hALR was correctly inserted into the vector. The rhALR was successfully expressed in E.Coli. Its MW. With 1. 5A10(4) was in correspondence with theoretic value and its amount is 30% of total bacteria protein. It existed not only in supernatant but also in precipitation of broken bacteria. CONCLUSION: The successes in construction of expressive vector of hALR and in expression of rhALR in E.Coli. make it possible to study further on its biological functions and antibody preparation.

Cloning, Molecular↗
PubMed2000

[Effect of lipoprotein lipase gene polymorphism on plasma lipid levels,BMI and subcutaneous fat distribution in simple obesity children].

OBJECTIVE: To assess the effect of Hind III DNA polymorphism in the lipoprotein lipase(LPL) gene on plasma lipid levels, body mass index(BMI) and subcutaneous fat distribution in simple obesity children. METHODS: The polymerase chain reaction(PCR) and restriction fragment length polymorphism(RFLP) techniques were used to detect the Hind III-LPL genotypes in 92 children with simple obesity. The levels of the plasma lipid, plasma lipoproteins, BMI and skinfold thickness at three measuring points(biceps, subscapular and abdominal wall) were also measured. RESULTS: The levels of TG, TC, LDL-C, Apo B, BMI, biceps and subscapular skinfold thickness with the average value of three measuring points in the obesity children with H(+) H(+)-LPL genotype were significantly higher than those in the obesity children with H(+) H(-)-LPL genotype. CONCLUSION: LPL-Hind III polymorphism may modify the levels of plasma lipid. plasma lipoproteins and BMI in children with simple obesity, and in the mean while it may affect the distribution of subcutaneous fat.

Body Mass Index↗
PubMed2000

Impact of genetic polymorphisms in cytochrome P450 2E1 and glutathione S-transferases M1, T1, and P1 on susceptibility to esophageal cancer among high-risk individuals in China.

Esophageal cancer, which is prevalent in China, is believed to be induced by environmental carcinogens such as nitrosamines and other agents. The disproportionate geographical distribution of this cancer among individuals suggests a role for gene-environment interactions in developing the disease. We have shown in our preliminary study that a genetic polymorphism in cytochrome P450 2E1 (CYP2E1) that is known to activate nitrosamines may be a susceptibility factor involved in the early events leading to the development of esophageal cancer (Lin et al., Cancer Epidemiol. Biomark. Prev., 7: 1013-1018, 1998). This relatively larger study was conducted to compare the results with our previous findings. One hundred and fifty cases with esophageal cancer, 146 cases with esophageal dysplasia, and 150 normal controls were residents of Linxian, China, a high-risk area. Genomic DNA samples were assayed for restriction fragment length polymorphisms in the CYP2E1 and GSTP1 loci by PCR amplification followed by digestion with RsaI and Alw26I, respectively. Deletion of the GSTM1 and GSTT1 genes was detected by multiplex PCR. The distribution of CYP2E1 c1/c1 allele frequency was found to be significantly different between controls (44.0%) and cases with cancer (71.3%) or cases with dysplasia (70.6%; P < 0.0001). Individuals having the c1/c1 genotype were at a 3.1-fold [95% confidence interval (CI), 2.4-3.9] increased risk of developing dysplasia and a 3.2-fold (95% CI, 2.5-4.1) increased risk of developing squamous cell carcinoma of the esophagus. Although polymorphisms in the GSTT1 and GSTP1 were not significantly different between cases with cancer or cases with dysplasia and controls, the frequency of the GSTM1 non-null (+/+ and +/0) genotypes appeared to be overrepresented in cases with cancer compared with controls (odds ratio, 2.3; 95% CI, 1.8-3.0). Furthermore, a joint effect of the CYP2E1 c1/c1 genotype and GSTM1 non-null genotype on the cancer risk was observed, showing an odds ratio of 8.5 (95% CI, 3.7-19.9). These results demonstrate that CYP2E1 and perhaps GSTM1 are genetic determinants in the development of squamous cell carcinoma of the esophagus.

Carcinoma, Squamous Cell↗