Biomedical subjects

Qi Liu

Publications and source records attributed to Qi Liu.

At least 55 records · Page 3Linked to original sources

PubMed2005

Replication of hepatitis B virus in primary duck hepatocytes transfected with linear viral DNA.

AIM: To explore the expression and replication of hepatitis B virus (HBV) DNA in primary duck hepatocytes (PDHs). METHODS: Complete HBV genome was transfected into PDHs by electroporation (transfected group, 1.19 x 10(12) copies of linear HBV DNA/1 x 10(7) PDHs). After 1-5 d of transfection, HBsAg and HBeAg in the supernatant and lysate of PDHs were measured with the IMX System. Meanwhile, replicative intermediates of HBV DNA were analyzed by Southern blotting and Dot blotting. PDHs electroporated were used as control group. RESULTS: HBsAg in the hepatocyte lysates of transfected group was 15.24 (1 d), 14.55 (3 d) and 5.13 (5 d; P/N values, positive > or =2.1) respectively. HBeAg was negative (<2.1). Both HBsAg and HBeAg were negative in the supernatant of transfected group. Dot blotting revealed that HBV DNA was strongly positive in the transfected group and negative in the control group. Southern blot analysis of intracellular total DNA indicated that there were relaxed circular (rc DNA), covalently closed circular (ccc DNA), and single-stranded (ss DNA) HBV DNA replicative intermediates in the transfected group, there was no integrated HBV DNA in the cellular genome. These parameters were negative in control group. CONCLUSION: Expression and replication of HBV genes can occur in hepatocytes from non-mammalian species. HBV replication has no critical species-specificity, and yet hepatic-specific regulating factors in hepatocytes may be essential for viral replication.

Animals↗

PubMed2005

Detecting correlation between sequence and expression divergences in a comparative analysis of human serpin genes.

Physiological functions and characteristic structures of the serpin gene superfamily have been studied extensively, yet the evolution of the serpin genes remains unclear. Gene duplication in this superfamily may shed light on this issue. Two models are used to predict the preservation of duplicated genes: the classical model and the duplication-degeneration-complementation (DDC) model. In this study, we analyzed the phylogenetic relationships of 33 human serpin genes and the expression data of some members of the serpin superfamily from a DNA microarray of human leukemia U937 cells with stably inducible expression of the leukemia-related AML1-ETO gene. We then determined the utility of the DDC model by mapping serpin superfamily expression data to the phylogenetic tree. The correlation between sequence and expression divergences as measured by the Pearson correlation coefficient indicated that human serpin genes evolved under the DDC model. Our study provides a new strategy for comparative analysis of gene sequences and microarray data.

Cell Line, Tumor↗

PubMed2005

Refined phylogenetic profiles method for predicting protein-protein interactions.

MOTIVATION: The increasing availability of complete genome sequences provides excellent opportunity for the further development of tools for functional studies in proteomics. Several experimental approaches and in silico algorithms have been developed to cluster proteins into networks of biological significance that may provide new biological insights, especially into understanding the functions of many uncharacterized proteins. Among these methods, the phylogenetic profiles method has been widely used to predict protein-protein interactions. It involves the selection of reference organisms and identification of homologous proteins. Up to now, no published report has systematically studied the effects of the reference genome selection and the identification of homologous proteins upon the accuracy of this method. RESULTS: In this study, we optimized the phylogenetic profiles method by integrating phylogenetic relationships among reference organisms and sequence homology information to improve prediction accuracy. Our results revealed that the selection of the reference organisms set and the criteria for homology identification significantly are two critical factors for the prediction accuracy of this method. Our refined phylogenetic profiles method shows greater performance and potentially provides more reliable functional linkages compared with previous methods.

Algorithms↗

PubMed2005

Local gene transduction of cyclooxygenase-1 increases blood flow in injured atherosclerotic rabbit arteries.

BACKGROUND: Cyclooxygenase-1 (COX-1) is the rate-limiting component in the synthesis of prostacyclin (PGI2), an important vasodilator and antithrombotic molecule. In balloon-injured, atherosclerosis-free porcine arteries, COX-1 gene transduction increases PGI2 production, induces durable vasodilation, and reduces thrombus formation. We tested the effectiveness of COX-1 local gene transduction for the prevention of postangioplasty restenosis in atherosclerotic arteries in a hypercholesterolemic rabbit model. METHODS AND RESULTS: We injured 1 carotid artery in 43 Watanabe heritable hyperlipidemic rabbits and performed local gene transduction using a viral vector containing the COX-1 gene (AdCOX-1, n=22) or no genes (Adnull, n=21). Three days later, AdCOX-1-treated arteries stimulated with arachidonic acid produced 100% more PGI2 (P<0.01), 400% more prostaglandin E2 (PGE2) (P<0.01), 400% more prostaglandin E1 (PGE1) (P<0.01), and 250% more cAMP (P<0.05) than Adnull-treated arteries. Twenty-eight days after treatment, Doppler sonography showed that blood flow velocity was preserved in AdCOX-1-treated arteries (ratio 0.92, injured compared with contralateral uninjured carotid artery) but reduced in Adnull-treated arteries (ratio 0.39), suggesting that AdCOX-1 prevented restenosis after injury. COX-1-transduced arteries also showed 80% greater lumen area 28 days after injury (P<0.01). CONCLUSIONS: The effectiveness of COX-1 in preventing restenosis and preserving normal blood flow 28 days after injury results from increased lumen area caused by durable vasodilation. COX-1 efficacy correlates with an early increase in the production of PGI2, PGE2, PGE1 (known to cause vasodilation), and cAMP. These results demonstrate for the first time that COX-1 gene transduction is an effective treatment for the prevention of postangioplasty restenosis of atherosclerotic arteries under clinically relevant conditions.

Angioplasty, Balloon↗

PubMed2005

On the electronic structure of ethidium.

The electronic structure of the common intercalating agent ethidium bromide (3,8-diamino-5-ethyl-6-phenylphenanthridinium bromide) is dominated by an interplay of electron donating and withdrawing effects mediated by its nitrogen atoms. X-ray crystallography, UV/Vis and IR absorption, fluorescence emission, and NMR spectroscopy are used to probe the electronic properties of the phenanthridinium "core" of ethidium as well as its exocyclic amines and 6-phenyl groups. Interestingly, despite its positive charge, most of ethidium's aromatic carbon and hydrogen atoms have high electron densities (compared to both 6-phenylphenanthridine and benzene). The data suggest that electron donation by ethidium's exocyclic amines dominates over the electron withdrawing effects of its endocyclic iminium in their combined influence on the electron densities of these atoms. Ethidium's nitrogen atoms are, conversely, electron deficient where the 5-position is the most electropositive, followed by the 3-amino, and lastly the 8-amino group. These results have been used to generate an empirically-based pi-electron density map of ethidium that may prove useful to understanding its nucleic acid binding specificity.

Crystallography, X-Ray↗

PubMed2005

[Inhibition of transcription and expression of X gene by lamivudine].

OBJECTIVE: The X protein of the hepatitis virus B plays an important role in the development of hepatocellular carcinoma (HCC). In this experiment we studied the effects of lamivudine on replication, transcription and expression of the X gene. METHODS: The replication of transfected X gene was measured by polymerase chain reaction. The mRNA of transfected X gene was analyzed by reverse transcriptase polymerase chain reaction. The expression of X protein was detected by biosensor. Moreover, we studied if these effects changed in a dose and time dependent manner. RESULTS: The OD data of purpose band reflected the replication of X gene for control and lamivudine groups were 151.4+/-3.5 and 144.0+/-11.4, respectively. The transcription of mRNA for X gene could be inhibited by lamivudine at a concentration of 4.36 x 10(-4) mol/L for 24 h. The OD data of purpose band for control and treatment groups (16 h) were 243.9+/-9.0 and 133.2+/-7.8. The inhibition was enhanced with the increase of lamivudine concentration and reacting time. The expression of the X protein in HepG2x cells was suppressed by lamivudine at a concentration of 4.36 x 10(-4) mol/L for 16 hours. The resonance unit for expression of the X protein decreased from 353.3+/-15.9 to 252.3+/-18.8. CONCLUSION: Although the replication of transfected X gene of HepG2x cells is not influenced by lamivudine, it may significantly inhibit the transcription and expression of the X protein.

Carcinoma, Hepatocellular↗

PubMed2005

[Establishing a rat insulin-resistant fatty liver model].

OBJECTIVE: To create a rat insulin resistant fatty liver model. METHODS: 14 male Wistar rats were randomly divided into a model and a control group. The model rats were fed a high-fat diet (45% of energy from fat) for 8 weeks, and the control group a standard diet (19% of energy from fat). Insulin sensitivity was measured with glucose infusion rate (GIR) by the euglycermic hyperinsulinemia clamp technique. The aminotransferase, triglyceride (TG), free fatty acid (FFA), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by biochemical methods, and insulin was measured by radioimmunoassay. The histological and ultrastructural changes of all rat livers were scored using light and electron microscopy. RESULTS: Rats fed the high-fat diet developed panlobular macrovesicular steatosis, lobular inflammatory cell infiltration and abnormal mitochondria, whereas those fed the standard diet had normal livers. All model group rats had elevated levels of aminotransferase, TG, FFA, insulin and liver index, and low GIR. In addition, the high-fat diet increased MDA and decreased SOD. CONCLUSION: A fatty liver and insulin resistance model was successfully developed in rats fed a high-fat diet for 8 weeks, which provided a useful experimental tool for elucidating pathogenesis and treatment of fatty liver.

Animals↗

PubMed2005

[Expression of augmenter of liver regeneration in hepatic tumor cells and its clinical significance].

OBJECTIVE: To investigate the effects of augmenter of liver regeneration (ALR) on the proliferation of hepatocytes and hepatic tumor cells and the expression of ALR in herpatocellular carcinoma (HCC). METHODS: Primary rat hepatocytes, QGY and HepG2 cells were cultured separately with ALR from different species. Cell proliferation was detected by their 3H-TdR uptake. The expression of ALR was examined in 9 normal hepatic tissues and 21 HCC cases using immunohistochemistry method. RESULTS: Different ALRs could stimulate the proliferation of HepG2 and QGY cells in a dose-dependent way in vitro, but all ALR had no influence in the proliferation of primary rat hepatocytes. The expression of ALR was absent in normal hepatic tissues, but present in all HCC hepatic tissues. However, the expression of ALR had no relationship with the differentiation and size of the carcinomas. CONCLUSION: ALR might play an important role in the occurrence and development of HCC.

Animals↗

PubMed2005

[Influence of angiotensin-converting enzyme gene polymorphism on the anti-proteinuria efficacy of angiotensin-converting enzyme inhibitor in Han nationality of southern Sichuan province in China].

OBJECTIVE: To investigate the association between angiotensin-converting enzyme (ACE) gene polymorphism and the reducing urinary protein efficacy of angiotensin-converting enzyme inhibitor (ACEI) in patients with primary chronic glomerulonephritis in Han nationality of southern Sichuan province. METHODS: Ninety-nine primary glomerulonephritis patients with urinary protein were enrolled in this study. They were treated with benazepril for at least 3 months. The ACE gene insertion/deletion(I/D) polymorphisms in intron 16 were determined by PCR. A comparison of the reducing urinary protein efficacy of benazepril was made between the patients with different ACE genotypes. RESULTS: Urinary protein excretion was significantly higher in patients with ACE DD genotype than that in patients with II genotype. After benazepril treatment for 3 months, the rates of urinary protein decline were observed. The rates of reduction of proteinuria in patients with DD genotype and ID genotype were obviously higher than that in patients with II genotype(P<0.05). CONCLUSION: Benazepril could decline the rate of urinary protein excretion in patients with primary chronic glomerulonephritis, and significant relationship was observed between ACE gene polymorphism and the reducing urinary protein efficacy of ACEI.

Adolescent↗

PubMed2005

[Natural history of small hepatocellular carcinoma: studied by MRI].

OBJECTIVE: To study natural history of small hepatocellular carcinoma (sHCC) and value of MRI in this research. METHODS: From 1999 to 2002, serial MR imagings were performed in 192 patients with cirrhosis no less than twice in order to detect sHCC focus. Characteristic MRI findings of focus were analysed. Diameters of focus (D) were measured. Tumorigenesis detected time (T) was counted; T and D were analysed by statistics and tumor volume doubling time (T(d)) was calculated. RESULTS: Fifty-eight new tumor foci in 33 patients were found, including 31 foci in 23 patients developed on the basis of cirrhosis, with a 12.0% cumulative tumorigenic rate of three years. The tumorigenesis detected time (T) was 386.9 +/- 256.4 days and the maximum diameter (D) was 2.258 +/- 1.074 cm. T was statistical correlated with D(3) (P < 0.01) and regressive formulas were established: D(3) = -2.69 + 0.058T (P = 0.0007), D(3) = -72.13 + 16.04lnT (P = 0.0064). Tumor volume doubling time was 20 approximately 279 days (mean: 104 days). CONCLUSION: The percentage of tumorigenesis is high in patients with cirrhosis. Regular MRI examinations are necessary to detect sHCC early. The optimal interval time is 3 approximately 6 months.

Adult↗

PubMed2005

[Effects of metformin on fatty liver in insulin-resistant rats].

OBJECTIVES: To investigate the effects of metformin on fatty livers in insulin-resistant rats. METHODS: Thirty-one male Wistar rats were randomly divided into a normal (n=8) and an experimental group (n=23). The normal group rats were fed a standard diet, and those of the experimental group with a high-fat diet. After 8 weeks, 7 rats from the experimental group were sacrificed to verify whether the model was established successfully. Then the experimental group was randomly subdivided into two groups: one with metformin treatment (n=8) and one without (n=8). After 6 weeks, insulin sensitivity was measured with glucose infusion rate (GIR) by euglycermic hyperinsulinemia clamp technique. Aminotransferase, triglyceride (TG) and free fatty acids (FFA) were measured by biochemical methods, insulin by radioimmunoassay and tumor necrosis factor-alpha (TNF alpha) by ELISA. The steatosis changes and inflammation activity of all rat livers were scored histologically. RESULTS: Compared with the model group, the insulin resistance, liver index, visceral adiposity and weight loss of the metformin group were dramatically ameliorated. The steatosis and the inflammatory activity in the livers and the level of serum aminotransferase of the metformin group were also significantly decreased. Furthermore, metformin treatment lowered serum TG, liver lipid accumulation and the production of FFA and TNF alpha. CONCLUSION: Metformin can significantly improved insulin resistance and fatty liver development in rats fed a high-fat diet. It may become a new choice for fatty liver treatment in the future.

Animals↗

PubMed2005

[Enrichment characteristics of heavy metals in heron eggs].

In this study, the eggs and tissues of black-crowned night heron, little egret, Chinese pond heron and cattle egret were sampled from the Dashu, Yuantong and Taizi mountains in Hefei areas of Anhui Province in April to June 2004, and the residual amounts of Cd, Pb and Cr in the samples were determined by atomic absorption spectrophotometry. The results showed that the test heavy metals could be detected at high levels in the eggshell, egg contents, and tissues of most samples. Eggshell and bone were the two main sites for heavy metals enrichment. Eggshell had significantly higher residues of the heavy metals than egg contents, implying that heavy metals could be excreted by eggshells. The residues of heavy metals in eggshell ranked as Cr > Pb > Cd, and had significant differences among species. Of the three heavy metals, Cr showed the most variation among species, being the highest in eggshell of Chinese pond heron and the lowest in that of cattle egret, but in egg contents, there was no significant difference among species. The variation of Cr residues among species was the second, being the highest in the egg contents of Chinese pond heron but not detected in that of cattle egret. The residues of Pb among species varied little. Since eggshell was easy to collect, it was practical to use it as the indicator to assess the pollution status of wetlands.

Animals↗

PubMed2005

[Imaging evaluation of efficacy of radiofrequency ablation treatment for hepatic cancer].

OBJECTIVE: To investigate the value of B-ultrasonography, CT and MRI in the evaluation of efficacy of radiofrequency ablation (RFA) for hepatic cancer. METHODS: One hundred patients with hepatic cancer were treated by ultrasound-guided RFA between October 1999 and September 2000. All patients had been examined by serum AFP, B-ultrasound, CT or MRI before and within one month after RFA. RESULTS: Before RFA, 34 patients who had had CT, the tumor showed hypo- or iso-density un-enhancement and enhancement on dynamic scanning. After RFA, 14 patients were examined by CT scan. Compared with the density on CT scan before RFA, 5 patients showed lower density lesion without any enhancement on dynamic scanning, but the other 9 patients showed similar images to the previous CT scan before RFA in some parts of their tumor. Before RFA, 66 patients examined by MRI showed hypo-intensity on T(1)-weighted image, hyper-intensity on T(2)-weighted image and enhancement on dynamic scanning. After RFA, among 86 patients examined by MRI, 44 showed iso- or hyper-intensity on T(1)-weighted image, iso- or hypo-intensity on T(2)-weighted image and no enhancement on dynamic scanning. But 42 patients showed similar images to the previous MRI imaging performed before RFA in some parts of their tumor. CONCLUSION: Both CT and MRI can be used as imaging evaluation tool on the effect of radiofrequency ablation for hepatic cancer. However, MRI is better than CT to detect whether the tumor is necrotic or still partly viable after radiofrequency ablation. Patients can be regarded as clinically cured provided that the serum AFP declines to the normal level from abnormally high level and/or MRI or CT scans show a complete necrotic lesion after RFA.

Adult↗

PubMed2004

Synthesis of N-methylpyrrole and N-methylimidazole amino acids suitable for solid-phase synthesis.

New and higher yielding synthetic routes to N-protected N-methylpyrrole and N-methylimidazole amino acids are introduced to circumvent difficulties associated with established schemes. Key steps in each synthesis include copper-mediated cross-coupling reaction to directly install a carbamate-protected 4-amine in the N-methylpyrrole derivative and effective nitration followed by a one-pot reduction/Boc protection of the amine in the synthesis of the N-Me-imidazole amino acid.

Amino Acids↗

PubMed2004

Segmental motion adjacent to an instrumented lumbar fusion: the effect of extension of fusion to the sacrum.

STUDY DESIGN: We present an in vitro biomechanical comparison of adjacent segment motion at the cranial segment (L3-L4) for an L4-L5 versus an L4-S1 fusion model using cadaveric lumbosacral spines. OBJECTIVES: The purpose is to determine the biomechanical effect on the unfused cranial segment of extending a short lumbar fusion to the sacrum versus stopping at L5. SUMMARY OF BACKGROUND DATA: Radiographic evidence of adjacent segment degeneration can occur as a late sequela in patients following lumbar and lumbosacral spinal fusions. It is believed that altered biomechanics adjacent to the fusion construct contribute to these degenerative changes. Little is known regarding changes in cranial adjacent segment mechanics resulting from inclusion of the sacrum compared to ending a fusion at L5. METHODS: Seven human cadaveric lumbosacral spines were instrumented with pedicle screws at L4, L5, and S1. Rods were placed from L4-L5 and from L4-S1 to simulate the corresponding fusion models. A material testing system was used to apply load-controlled moments to the spines in flexion-extension, lateral bending, and axial rotation. Electromagnetic sensors were used to record 6 df motion across the L3-L4, L4-L5, and L5-S1 motion segments. Angular displacements were recorded and system stiffness was calculated for each spine and construct. A paired sample t test was used to determine significance of recorded differences. RESULTS: Under flexion-extension loading, the angular displacement in the sagittal plane at L3-L4 for the L4-S1 model was 9.0 degrees compared to 7.8 degrees for the L4-L5 model (+15%; P = 0.002). Under lateral bending loading, L3-L4 motion in the coronal plane for the L4-S1 model was 12.8 degrees and was 14.5 degrees for the L4-L5 model (-12%; P = 0.002). In axial rotation testing, L3-L4 torsional motion for the L4-S1 model was equivalent to the L4-L5 model. Overall system stiffness increased for the L4-S1 model compared with the L4-L5 model. CONCLUSIONS: In this load-controlled model, extending fusion across L5-S1 did not consistently increase motion at L3-L4. While it may be difficult to translate this finding to a clinical setting, avoiding fusion to the sacrum in a lower lumbar fusion may not provide significant benefit from the standpoint of avoiding adjacent segment disease.

Adult↗

PubMed2004

Expression of human augmenter of liver regeneration in pichia pastoris yeast and its bioactivity in vitro.

AIM: To construct a yeast expression system of human augmenter of liver regeneration (hALR) and to examine its bioactivity in vitro. METHODS: With PCR and gene recombination techniques, cDNA of open reading frame of hALR was obtained from recombinant plasmid pcDNA3.1-hALR and inserted into plasmid pPIC9. The cDNA of hALR from recombinant plasmid pPIC9-hALR demonstrated by sequencing was subcloned into plasmid pPIC9K. The recombinant plasmid pPIC9K-hALR was transformed into GS115 with electroporation. hALR was expressed by GS115 under the induction of 5 mL/L methanol and purified with ultrafiltration after it was analyzed by 15% SDS-PAGE and Western blot. The effects of hALR on in vitro proliferation of QGY and HepG(2) cells were evaluated by (3)H-TdR methods. RESULTS: The correctness and integrity of recombinant plasmids pPIC9-hALR and pPIC9K-hALR were identified by restriction digestion, PCR and sequencing methods, respectively. hALR as a secretive protein was successfully expressed by GS115. Its molecular weight was about 15 ku and the target protein was about 60% of the total protein in the supernatant from GS115 with plasmid pPIC9K-hALR. The results of Western blot of hALR showed the specific band. The high qualitative hALR was obtained through ultrafiltration. hALR could stimulate in vitro proliferation of QGY and HepG(2) cells in a dose-dependent manner, but there was a difference in reactivity to hALR between QGY and HepG(2). CONCLUSION: The hALR as a secretive protein can be successfully expressed by GS115. It may stimulate in vitro proliferation of QGY and HepG(2) cells at a dose-dependent manner. But QGY and HepG(2) cells have different reactivities to hALR.

Blotting, Western↗

PubMed2004

[Percutaneous radiofrequency ablation for liver cancer located in hepatis].

OBJECTIVE: To explore the feasibility, effect and problems of percutaneous radiofrequency ablation (PRFA) performed for small liver cancer located in hepatis. METHODS: Twenty-one patients, who had small primary or metastatic liver cancer confirmed clinically or pathologically that were located in hepatis and less than 5 cm, were performed PRFA between April 2000 and October 2002. All patients were followed up to examine the value of AFP, MRI or CT. Kaplan-Meier estimation was used for the disease-free survival rate and the long-term survival rate. RESULTS: The rate of AFP positive down to negative was 77.8% (7/9). The complete necrosis rate was 90.5% (19/21). The peri-tumor recurrence-free survival rates of 0.5-, 1-, 1.5-, 2-year were all 94.7%. The distant recurrence-free survival rates of 0.5-, 1-, 1.5-, 2-year were 90.0%, 77.1%, 77.1% and 77.1% respectively. The whole survival rates of 0.5-, 1-, 1.5- and 2-year were 89.2%, 82.8%, 82.8% and 55.2% respectively. CONCLUSIONS: Small liver cancer located in hepatis was not the contra-indication of PRFA. If the puncture point and route is selected properly, electrodes outspreaded exactly and the range of heating controlled appropriately, PRFA is an effective method and of less complication rate for small liver cancer located in hepatis. Sometimes, PRFA can be combined with TACE for those tumors of the diameter larger than 3 cm.

Adult↗

PubMed2004

Scoring hidden Markov models to discriminate beta-barrel membrane proteins.

A new method is presented for identification of beta-barrel membrane proteins. It is based on a hidden Markov model (HMM) with an architecture obeying these proteins' construction principles. Once the HMM is trained, log-odds score relative to a null model is used to discriminate beta-barrel membrane proteins from other proteins. The method achieves only 10% false positive and false negative rates in a six-fold cross-validation procedure. The results compare favorably with existing methods. This method is proposed to be a valuable tool to quickly scan proteomes of entirely sequenced organisms for beta-barrel membrane proteins.

Algorithms↗