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Gang Liu

Publications and source records attributed to Gang Liu.

At least 55 records · Page 3Linked to original sources
PubMed2006

2,4-diaminopyrimidine derivatives as potent growth hormone secretagogue receptor antagonists.

Ghrelin, a gut-derived orexigenic hormone, is an endogenous ligand of the growth hormone secretagogue receptor (GHS-R). Centrally administered ghrelin has been shown to cause hunger and increase food intake in rodents. Inhibition of ghrelin actions with ghrelin antibody, peptidyl GHS-R antagonists, and antisense oligonucleosides resulted in weight loss and food intake decrease in rodents. Here we report the effects of GHS-R antagonists, some of which were potent, selective, and orally bioavailable. A structure-activity relationship study led to the discovery of 8a, which was effective in decreasing food intake and body weight in several acute rat studies.

Animals↗
PubMed2006

Effect of Agkistroden blomhoffi (mamushi) on superoxide generation in human neutrophils.

BACKGROUND: The purpose of this study is to investigate the effect of Agkistroden blomhoffi (mamushi) aqueous extract on stimulus-induced superoxide generation in human neutrophils. METHODS: Superoxide generation was assayed by measuring the reduction of ferricytochrome C (cyt c) using a dual-beam spectrophotometer. The phosphorylation of neutrophil proteins and the translocation of cytosolic compounds to the cell membrane were detected using specific monoclonal antibodies. RESULTS: Mamushi aqueous extract markedly suppressed fMLP-induced superoxide generation in a concentration-dependent manner. fMLP-induced translocation of cytosolic compounds p47phox, p67phox and Rac to the cell membrane was suppressed in parallel to the suppression of superoxide generation. The fractions with MW below 10 kDa dose-dependently suppressed tyrosyl phosphorylation of 45.0, 77.6 and 99.5 kDa proteins in fMLP-treated human neutrophils; the inhibition of tyrosyl phosphorylation was in parallel to that of the fMLP-induced translocation of p47phox to the cell membrane and superoxide generation. CONCLUSIONS: Mamushi aqueous extract markedly suppressed fMLP-induced superoxide generation in human neutrophils and also suppressed the translocation of cytosolic compounds to the cell membrane and tyrosyl phosphorylation of proteins. The efficacious components are the fractions with MW below 10 kDa. O-phosphoserylethanolamine, a new dipeptide isolated from mamushi, also suppressed fMLP-induced superoxide generation in human neutrophils in a dose-dependent manner.

Agkistrodon↗
PubMed2006

Guided alignment and positioning of single DNA molecules by a structured contact line on a block copolymer surface.

A nanostructured dynamical contact line is generated when the meniscus of a droplet of water solution is moving on the structured surface of a thin film of a block copolymer of poly(styrene-b-methyl methacrylate) (PS-b-PMMA) because of the difference in the water contact angles on PS and PMMA. Such a structured receding contact line extends DNA molecules as in the molecular combing process. More importantly, it aligns DNA molecules following the position and orientation of the PMMA domains on the surface. The driving force of this phenomenon is discussed as the lateral motion of the locally modified contact line.

Acrylic Resins↗
PubMed2006

Treatments for pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a devastating disease that leads to right heart failure and premature death. Historically, we are restricted by limited options for drug treatment. Over the past decade, with advances in our understanding of pathophysiological and molecular mechanisms, many new therapeutic strategies (synthetic prostacyclin and prostacyclin analogues, endothelin receptor antagonists and sildenafil) have been developed for the treatment of PAH, and the clinical efficacy has been tested in many randomized-controlled trials (RCTs). In this overview, we review the evidence for the use of historical and new treatments that arises from the Cochrane Collaboration of Systematic Reviews and from recent RCTs.

Antihypertensive Agents↗
PubMed2006

Synthesis and SAR of 1,9-dihydro-9-hydroxypyrazolo[3,4-b]quinolin-4-ones as novel, selective c-Jun N-terminal kinase inhibitors.

A novel class of 1,9-dihydro-9-hydroxypyrazolo[3,4-b]quinolin-4-ones as c-Jun-N-terminal kinase (JNK) inhibitors is described. These compounds were synthesized via the condensation of 2-nitrobenzaldehydes and hydroxypyrazoles. The structure-activity relationships (SAR) and kinase selectivity profile of the inhibitors are also discussed. Compound 16 was identified as a potent JNK inhibitor with good cellular potency.

Crystallography, X-Ray↗
PubMed2006

Regulation of the p53 transcriptional activity.

In response to various stresses, p53 is rapidly activated and transcriptionally regulates a number of target genes by which p53 modulates a variety of cellular activities. The transcriptional activity of p53 is delicately regulated by a plethora of cellular factors, independently or synergistically, in multiple ways in order to achieve a specific response. This article reviewed the role of the basal transcriptional machinery, co-activators, and co-repressors involved in p53-dependent transcription, and the underlying mechanism by which the p53 transcriptional activity is regulated. We also discussed some potentially interesting questions and future directions in the field.

Animals↗
PubMed2006

SanJ, an ATP-dependent picolinate-CoA ligase, catalyzes the conversion of picolinate to picolinate-CoA during nikkomycin biosynthesis in Streptomyces ansochromogenes.

Nikkomycins, a group of peptidyl nucleoside antibiotics, are competitive inhibitors of chitin synthase. The nikkomycin biosynthetic gene cluster has been cloned previously from Streptomyces ansochromogenes. The cluster contains 25 complete ORFs including sanJ. The sanJ gene was inactivated by the insertion of a kanamycin resistance gene and the resulting disruption mutants failed to produce nikkomycins. Moreover, the nikkomycin production was restored by complementation with a single copy of sanJ. The deduced product of sanJ bears striking sequence similarity with enzymes belonging to the adenylate-forming superfamily. sanJ was overexpressed as a His6-tagged fusion protein in Escherichia coli and purified to apparent homogeneity by affinity chromatography. The purified SanJ demonstrated adenylate ligase activity in the presence of picolinate or its analogs (benzoate, nicotinate, 4-methoxybenzoate, 4-hydroxybenzoate), ATP and Mg2+. SanJ was also found to catalyze the conversion of picolinate, benzoate, nicotinate to their corresponding CoA esters and 4-methoxybenzoate, 4-hydroxybenzoate to their respective AMP derivatives in vitro. This was unambiguously shown by using HPLC and electrospray ionization mass spectrometry (ESI-MS) or by comparing the reaction product with an authentic standard of benzoyl-CoA. These results indicated that sanJ encodes an ATP-dependent picolinate-CoA ligase which is essential for nikkomycin biosynthesis.

Adenosine Triphosphate↗
PubMed2006

[Vagal effects on inducibility of atrial fibrillation at different sites of pulmonary veins after autonomic denervation].

OBJECTIVE: To investigate the vagal effects on the inducibility of atrial fibrillation (AF) at different sites of pulmonary vein after autonomic denervation. METHODS: The bilateral cervical vagal trunks of 10 male mongrel dogs were isolated and decentralized. The ansae subclaviae were exposed, ligated, and cut. Needle electrodes were inserted into the subcutaneous tissue of the 4 extremities to record the myocardiogram. Right ventricle electrode was introduced via femoral vein and an electrode with 4 poles was sutured with the right appendage (RAA), left appendage (LAA), left atrium (LA), left superior pulmonary vein (LSPV), right superior pulmonary vein (RSPV), left inferior pulmonary vein (LIPV), and right inferior pulmonary vein (RIPV) respectively. Local burst stimulation (S1S1 = 80 ms, impulse duration = 0.5 ms) was performed on these sites to record the baseline AF inducibility. When sinus cardiac arrest for 2 s or complete atrio-ventricular block occurred programmed bilateral vagal nerves stimulation (VNS) was performed with the frequency of 12.5 Hz, impulse duration of 0.5 ms, and voltage of 5-8 V. Atropine 0.04 mg/kg was dripped intravenously. The changes of AV inducibility were observed. RESULTS: In the baseline state, S1S1 programmed stimulation on all the sites evoked single or multiple atrial premature beats and short runs of atrial tachycardia, only a few sites induced AF. However, S1S1 programmed stimulation combined with VNS significantly increased the frequencies of induced AV at the sites of 4 PVs (P < 0.05, P < 0.01). When atropine was dripped the AV induction rates at all sites did not changed significantly (all P > 0.05). CONCLUSION: Vagal nerve may play an important role in the initiation of AF originating from pulmonary veins.

Animals↗
PubMed2006

Distinct memory traces for two visual features in the Drosophila brain.

The fly Drosophila melanogaster can discriminate and remember visual landmarks. It analyses selected parts of its visual environment according to a small number of pattern parameters such as size, colour or contour orientation, and stores particular parameter values. Like humans, flies recognize patterns independently of the retinal position during acquisition of the pattern (translation invariance). Here we show that the central-most part of the fly brain, the fan-shaped body, contains parts of a network mediating visual pattern recognition. We have identified short-term memory traces of two pattern parameters--elevation in the panorama and contour orientation. These can be localized to two groups of neurons extending branches as parallel, horizontal strata in the fan-shaped body. The central location of this memory store is well suited to mediate translational invariance.

Adenylyl Cyclases↗
PubMed2006

Effect of five triterpenoid compounds isolated from root bark of Aralia elata on stimulus-induced superoxide generation, tyrosyl or serine/threonine phosphorylation and translocation of p47(phox), p67(phox), and rac to cell membrane in human neutrophils.

Five triterpenoids; Congmuyanoside V, X, XI, XII, and XV (Cong. V, X, XI, XII, and XV) were isolated from the root bark of Aralia elata. The effect of these triterpenoids on stimulus-induced superoxide generation in human neutrophils was assayed by measuring the reduction of ferricytochrome c (cyt. c) using a dual-beam spectrophotometer. Translocation of p47(phox), p67(phox), and rac to the cell membrane and tyrosyl or serine/threonine phosphorylation of neutrophil proteins were investigated using specific monoclonal antibodies. The five triterpenoids used in the present experiment significantly suppressed N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide generation in concentration-dependent manner. Congmuyanoside V, XII, and XV also suppressed arachidonic acid (AA)-induced superoxide generation in high concentration. However, these triterpenoids showed no effect on phorbol 12-myristate 13-acetate (PMA)-induced superoxide generation. fMLP- and AA-induced tyrosyl phosphorylation and translocation of the cytosolic proteins p47(phox), p67(phox), and rac to the cell membrane were suppressed in parallel with the suppression of the stimulus-induced superoxide generation.

Arachidonic Acid↗
PubMed2006

Optimization of 2,4-diaminopyrimidines as GHS-R antagonists: side chain exploration.

The synthesis and structure-activity relationships of the 4- and 6-substituents of 2,4-diaminopyrimidine-based growth hormone secretagogue receptor (GHS-R) antagonists are described. Diaminopyrimidines with 6-norbornenyl (4n) and 6-tetrahydrofuranyl (4p) substitutents were found to exhibit potent GHS-R antagonism and good selectivity (approximately 1000-fold) against dihydrofolate reductase.

Pyrimidines↗
PubMed2006

Detection of ischemic myocardium with a new hypoxic tissue targeting tracer 99Tc(m)-HL91.

The imaging appearances of 99Tc(m)-HL91, a new hypoxic imaging agent, in ischemic myocardium were studied and the value of 99Tc(m)-HL91 in the evaluation of regional ischemic viable myocardium was explored. Acute myocardial ischemia models were made by coronary artery legations in 18 rats and randomly divided into 2 groups: 99Tc(m)-HL91 group and 99Tc(m)-MIBI group. Evan blue infusion during ischemia and TTC staining after operation were used to delineate the area of ischemic and viable myocardium. The isolated heart was sliced in the short axis and then autoradiography was performed. The electron microscopic examination was also done for the myocardial samples. 99Tc(m)-HL91 and 99Tc(m)-MIBI uptake activities (counts/g) were measured in the area of ischemic myocardium (T) and normal myocardium (NT) separately. The uptake ratios of 99Tc(m)-HL91 and that of 99Tc(m)-MIBI in ischemic myocardium were calculated as T/NT. It was found that the normal myocardium was blue and ischemic or infarct myocardium was negative with Evans blue in all experiment rats. Both the normal and ischemic myocardium was in red color with TTC staining. In the 99Tc(m)-HL91 group the ischemic myocardium showed much higher uptake over normal myocardium, that was demonstrated both in the autoradiography and quantitative analysis. The ischemic/normal activity ratios were 1.634 +/- 0.354. It was suggested that 99Tc(m)-HL91 might accumulate in ischemic and viable myocardium, which is helpful in the evaluation of hypoxic but viable myocardium and potentially used as a imaging agent to assess myocardial viability.

Animals↗
PubMed2006

Cardiac video analysis using Hodge-Helmholtz field decomposition.

The critical points (also known as phase singularities) in the heart reflect the pathological change of the heart tissue, and hence can be used to describe and analyze the dynamics of the cardiac electrical activity. As a result, the detection of these critical points can lead to correct understanding and effective therapy of the tachycardia. In this paper, we propose a novel approach to address this problem. The proposed approach includes four stages: image smoothing, motion estimation, motion decomposition, and detection of the critical points. In the image smoothing stage, the noisy cardiac optical data are smoothed using anisotropic diffusion equation. The conduction velocity fields of the cardiac electrical patterns can then be estimated from two consecutive smoothed images. Using the recently developed discrete Hodge-Helmholtz motion decomposition technique, the curl-free and divergence-free potential surfaces of an estimated velocity field are extracted. Finally, hierarchically searching the minima and maxima on the potential surfaces, the sources, sinks, and rotational centers are located with high accuracy. Experimental results with four real cardiac videos show that the proposed approach performs satisfactorily, especially for the cardiac electrical patterns with simple propagations.

Algorithms↗
PubMed2006

[Dual promoters enhance heterologous enzyme production from bacterial phage based recombinant Bacillus subtilis].

The effect of dual promoters on recombinant protein production from bacterial phage based Bacillus subtilis expression system was investigated. Alpha amylase (from Bacillus amyloliquefaciens) and penicillin acylase (from Bacillus megaterium) were selected as the indicating enzymes. Both the promoterless genes and the promoter-bearing genes were isolated through PCR amplification with properly designed primers, and were inserted into plasmid pSG703 that contains the lacZ-cat expression cartridge. The lysogenic B. subtilis (phi105 MU331) was transformed with the resultant recombinant plasmids, and the heterologous genes were thereby integrated into the chromosommal DNA of B. subtilis via homologous recombination. The transformants were designated as B. subtilis AMY1, B. subtilis AMY2, B. subtilis PA1, and B. subtilis PA2, respectively. In the recombinant B. subtilis strains, the inserted sequences were located down stream of a strong phage promoter that could be activated by thermal induction. In B. subtilis AMY1 and B. subtilis PA1, transcription of the heterologous genes was only initiated by the phage promoter after heat shock, whereas in B. subtilis AMY2 and B. subtilis PA2, transcription of the heterologous genes was initiated by dual promoters, the phage promoter and the native promoter. The application of dual promoters increased the productivity of both enzymes, with 133% enhancement for alpha-amylase production and 113% enhancement for penicillin acylase production.

Bacillus Phages↗
PubMed2006

Enzymatic synthesis and characterization of novel biodegradable copolymers of 5-benzyloxy-trimethylene carbonate with 1,4-dioxan-2-one.

Enzymatic ring-opening copolymerization of 5-benzyloxy-trimethylene carbonate (BTMC) and 1,4-dioxan-2-one (DON) was investigated for the first time. Immobilized porcine pancreas lipase (IPPL) on silica particles was selected to perform the copolymerization. A series of novel biodegradable copolymers with different compositions were characterized by (1)H NMR, (13)C NMR, and GPC. The influences of reaction conditions such as polymerization time and catalyst concentration on the yield and molecular weight of the copolymers were also studied. The copolymerizations of different monomer feed ratios were carried out in bulk at 150 degrees C with 4.5 wt per thousand IPPL as a catalyst for 24 h. With the increase of the BTMC molar feed ratio from 20% to 79%, the M(n) of the resulting copolymers increased from 5600 to 63400. Water uptake and static contact angle experiments showed that the hydrophilicity of copolymers could be improved with increasing DON content in the copolymers. Moreover, the in vitro drug release rate (ibuprofen as the model drug) of the resulting copolymers also increased along with the DON content in the copolymers.

Analgesics, Non-Narcotic↗
PubMed2006

Concurrent antiglomerular basement membrane disease and immune complex glomerulonephritis.

Antiglomerular basement membrane (GBM) disease is characteristically described with linear deposition of IgG along GBM. However, the concurrent glomerular immune complex deposition was not rare and might be contributed to the development of anti-GBM disease. In the current series, glomerular immune complexes were identified in 10 of 47 patients who presented with renal-biopsy-proven anti-GBM disease. Six of the 10 patients complicated with a well-documented glomerulonephritis, including two patients with membranous nephropathy, one patient with IgA nephropathy, one patient with membranoproliferative glomerulonephritis, one patient with Schonlein-Henoch nephritis, and one patient with hepatitis B virus associated membranous nephritis. The other four patients had immune complexes with IgG or IgM predominance deposited in glomerular mesangium without a well-documented glomerulonephritis. Clinical and pathological data of patients with immune complex deposition (n = 10) were compared with those of patients with anti-GBM disease alone (n = 37). There was no significant difference in age, gender, clinical and pathological manifestations, and renal outcome between the two groups. In general, the association of glomerular immune complexes did not lead to a benign prognosis. Plasma exchange and extensive immunosuppressive therapy should be carried out as soon as possible. The immune complexes deposited in glomeruli might participate in the initiation of anti-GBM disease.

Adolescent↗
PubMed2006

Potent potentiating diuretic effects of prednisone in congestive heart failure.

UNLABELLED: Animal studies showed glucocorticoids could specifically dilate renal vasculature, regulate synthesis and release of atrial natriuretic peptide (ANP), upregulate ANP receptors on vascular endothelial cells, and thus have potent potentiating diuresis and natriuresis effects in animal studies; however, their diuretic efficacy in humans is yet to be known. Therefore, we designed this randomized, double- blind, placebo-controlled, clinical study to determine the diuretic efficacy of prednisone, a glucocorticoid, in patients with congestive heart failure (CHF). METHODS: Twenty clinically stable patients with CHF without overt fluid retention were randomized to a prednisone group or placebo group. Prednisone (1 mg/kg/day with a maximum dose of 60 mg/day) was added to standard care for 7 days, leaving other medications unchanged. Variables included urine volume and electrolytes, serum electrolytes, and change from baseline in serum creatinine. RESULTS: Adding prednisone resulted in striking diuresis and natriuresis with time. As compared with the placebo group, the maximum of mean daily urine volume was 810.5 mL larger than those in the placebo group (95% confidence intervals [CI] 276.25 to 1344.86, P < 0.05). The maximum mean daily sodium excretion was 123.8 mmol higher than those patients given placebo (95% CI 11.4 to 236.2, P < 0.05). The placebo-corrected effect on change from baseline in serum creatinine was -19.5 mumol/L (95% CI -7.4 to -31.6, P < 0.01), favoring prednisone. CONCLUSIONS: This pilot study showed that prednisone had potent potentiating diuretic effects in patients with heart failure and might improve renal function in the same time. Further prospective randomized clinical studies are warranted to determine the preferable dose and its efficacy in decompensated congestive heart failure.

Adult↗