Biomedical subjects

Gang Liu

Publications and source records attributed to Gang Liu.

At least 235 records · Page 13Linked to original sources

PubMed2002

Interactions of elongation factor 1alpha with F-actin and beta-actin mRNA: implications for anchoring mRNA in cell protrusions.

The targeting of mRNA and local protein synthesis is important for the generation and maintenance of cell polarity. As part of the translational machinery as well as an actin/microtubule-binding protein, elongation factor 1alpha (EF1alpha) is a candidate linker between the protein translation apparatus and the cytoskeleton. We demonstrate in this work that EF1alpha colocalizes with beta-actin mRNA and F-actin in protrusions of chicken embryo fibroblasts and binds directly to F-actin and beta-actin mRNA simultaneously in vitro in actin cosedimentation and enzyme-linked immunosorbent assays. To investigate the role of EF1alpha in mRNA targeting, we mapped the two actin-binding sites on EF1alpha at high resolution and defined one site at the N-terminal 49 residues of domain I and the other at the C-terminal 54 residues of domain III. In vitro actin-binding assays and localization in vivo of recombinant full-length EF1alpha and its various truncates demonstrated that the C terminus of domain III was the dominant actin-binding site both in vitro and in vivo. We propose that the EF1alpha-F-actin complex is the scaffold that is important for beta-actin mRNA anchoring. Disruption of this complex would lead to delocalization of the mRNA. This hypothesis was tested by using two dominant negative polypeptides: the actin-binding domain III of EF1alpha and the EF1alpha-binding site of yeast Bni1p, a protein that inhibits EF1alpha binding to F-actin and also is required for yeast mRNA localization. We demonstrate that either domain III of EF1alpha or the EF1alpha-binding site of Bni1p inhibits EF1alpha binding to beta-actin mRNA in vitro and causes delocalization of beta-actin mRNA in chicken embryo fibroblasts. Taken together, these results implicate EF1alpha in the anchoring of beta-actin mRNA to the protrusion in crawling cells.

Actins↗

PubMed2002

Tumor suppressor gene p16 and Rb expression in gastric cardia precancerous lesions from subjects at a high incidence area in northern China.

AIM: To further understand the molecular basis for gastric cardia carcinogenesis and to provide etiological clues. METHODS: Endoscopic mucosa biopsy and histopathological examinations were made on 37 subjects from a high incidence area for both esophageal and gastric cardia carcinomas in northern China. All the biopsy samples were fixed in 850 ml. (-1)L alcohol and embedded in paraffin. Each block contained one piece of tissue and was serially section at 5 microm. Immunohistochemistry (ABC) was carried out on these gastric cardia samples to determine the alterations of p16 and Rb. RESULTS: Based on the histopathlogical examination there were 11 cases of chronic superficial gastritis, 12 cases of chronic atrophic gastritis and 14 cases of dysplasia. The immunostaining demonstrated different levels of unclear immunostaining of p16 and Rb in normal gastric cardia tissue and the tissues with different severity of lesions. With the lesions progressing, the positive immunostaining rates for p16 protein had a decreasing tendency. In contrast, the positive immunostaining rate for Rb protein had an increasing tendency. There was a significant negative relationship between the two parameters. Changes of p16 was CSG 11(100%), CAG 7(58%), DYS 4(29%) and changes of Rb was CSG 2(18%), CAG 8(67%) and DYS 12(86%), (P<0.05). CONCLUSION: The alterations of p16 and Rb protein may play a role in the early stages of gastric cardia carcinogenesis.

China↗

PubMed2002

[Effect of insulin-like growth factor-I on cultured articular chondrocytes of rabbits].

OBJECTIVE: To investigate the influence of insulin-like growth factor-I (IGF-I) on biological characteristics of articular chondrocytes cultured in vitro of rabbits. METHODS: Monolayer articular chondrocytes of 4-week old rabbits were cultured in medium with IGF-I, at the concentrations of 3, 10, 30, 100, and 300 ng/ml. The DNA content in cells and glucuronic acid content in matrix were detected on the 2nd, 4th, 6th days after culture. RESULTS: The DNA content in cells and the glucuronic acid content in matrix in articular chondrocytes cultured in medium with IGF-I at concentrations of 3-300 ng/ml were all significantly higher than those in control group (P < 0.01), which reached the peak at the concentrations of 30-100 mg/ml on the 4th day. CONCLUSION: IGF-I could obviously promote the proliferation of articular chondrocytes in vitro, and there exist time-dependent and dose-dependent effect.

Animals↗

PubMed2002

[Molecular cloning of SRG2, a mouse testis spermatocyte apoptosis-related gene].

A novel mouse gene full-length cDNA sequence-SRG2 were identified (GenBank accession number AF395083), which was significantly changed in cryptorchidism, from a mouse testis cDNA library using a cDNA fragment (GenBank accession number BE644542) as an electronic probe. SRG2 was 1058 bp in length. The putative protein encoded by this gene was 295 amino acids with a theoretical molecular weight of 33 579 and isoelectric point of 9.64. The sequence shared no significant homology with any known protein in databases except TSARG2, with which its homology was 78%. RT-PCR showed that SRG2 was expressed significantly in testis.

Amino Acid Sequence↗

PubMed2002

[Familial membranous nephropathy: an analysis of 3 kindreds and literature review].

OBJECTIVE: To report three kindreds of familial membranous nephropathy and describe its clinical and pathological characteristics. METHODS: 6 patients with renal biopsy proved familial membranous nephropathy from 3 kindreds were described. Their clinical and pathological data were compared with 33 patients who were also suffering from familial membranous nephropathy from 16 kindreds documented in PubMed and 30 sporadic patients who were collected in our hospital with membranous nephropathy. RESULTS: Compared with the patients documented in the literatures, the patients were older and the ratios of male and female patients in this series were equal. In both series, the pathological lesions were severe. Compared with sporadic patients with membranous nephropathy, the patients in familial form had severer pathological lesions. There were no differences among all patients in clinical manifestations, such as proteinuria, hypertension and renal function. The major clinical symptom in familial membranous nephropathy patients was nephritic syndrome. CONCLUSIONS: The present study first reported the kindreds of familial membranous nephropathy in China. The clinical manifestations of familial membranous nephropathy in our patients, as well as in other familial cases reported to date, are similar with those in the non-familial membranous nephropathy patients, but the pathological changes in the familial cases were severer than those in the non-familial. To distinguish the familial form from idiopathic membranous nephropathy, it is essential to understand the genetic factors underlying this disease.

Adolescent↗

PubMed2002

Protein tyrosine phosphatase 1B as a target for the treatment of impaired glucose tolerance and type II diabetes.

Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of the insulin signal transduction cascade, initiated when insulin binds to the insulin receptor. PTP1B-deficient mice are more sensitive to insulin, and have improved glycemic control and resistance to diet-induced obesity than wild-type control mice. Diabetic mice treated with PTP1B antisense oligonucleotides intraperitoneally have lower PTP1B protein levels in liver and fat, reduced plasma insulin, blood glucose and hemoglobin A1c (HbA1c) levels. These studies validate PTP1B as a promising drug discovery target for the treatment of insulin resistance, diabetes and obesity. Herein we review the recent advances in the structure-based design of potent and selective small molecule inhibitors of PTP1B, and discuss th e challenge of developing compounds with improved cell permeability and bioavailability.

Animals↗

PubMed2002

[Analysis of preservatives in cosmetics by gas chromatography].

The wide bore capillary column HP-1701(15 m x 0.53 mm i.d. x 1.0 micron) has been used to analyze benzyl alcohol, methyl-p-hydroxy benzoate, ethyl-p-hydroxy benzoate, propyl-p-hydroxy benzoate, and butyl-p-hydroxy benzoate in cosmetics. The results showed that these preservatives could be separated with the capillary column completely and their peaks were not interfered with those of other components in cosmetics. The detection limits were 13 ng, 70 ng, 70 ng, 100 ng and 100 ng respectively and the linear range was 50 ng-500 ng.

Benzoates↗

PubMed2002

[Leaf photosynthetic acclimation of Echinochloa crusgalli grown in rice field to free-air CO2 enrichment (FACE)].

A comparative study was made between the leaves of Echinochloa crusgalli grown at 580 (FACE) and 380 (control, ambient air) mumol CO2 mol-1 air by observation of net photosynthetic rates (Pn) and the contents of soluble protein and the key enzyme of photosynthetic carbon assimilation, Rubisco. When measured at the ambient air CO2 concentration (380 mumol.mol-1), Pn were significantly lower in leaves grown under FACE conditions than that in those leaves grown in the ambient air. This indicates that photosynthetic acclimation to high CO2 occurs in the leaves grown under FACE conditions. Also, the stomatal conductance (Gs) and intercellular CO2 concentration (Ci) were decreased significantly in the leaves grown under FACE. The content of total soluble protein was much lower in the leaves grown under FACE conditions than that the in the control, and the content of Rubisco was also decreased in the FACE leaves, but the difference was not significant. From these results it is deduced that the photosynthetic acclimation to high CO2 in Echinochloa crusgalli leaves grown under FACE conditions is mainly related to the partial closure of stomata and the decrease in soluble protein containing some enzymes.

Acclimatization↗

PubMed2002

[Response and acclimation of photosynthesis in rice leaves to free-air CO2 enrichment (FACE)].

The net photosynthetic rate (Pn), water use efficiency (WUE), and apparent quantum yield of carbon assimilation of rice leaves were boserved contrastively under ambient air (380 mumol.mol-1 CO2) and FACE (580 mumol.mol-1CO2). The results showed that the observed index under FACE were significantly higher than those under ambient air. Nevertheless, along with the time of high CO2 treatment prolonged, the enhancement effect of high CO2 on net photosynthetic rate declined gradually. At the same CO2 concentration, Pn and carboxylation efficiency (CE) in rice leaves under FACE were lower than those under ambient air. Although the stomatal conductances in FACE leaves was obviously lower than that in ambient leaves, their intercellular CO2 concentrations were not significantly different, which implied that the photosynthetic down-regulation in rice leaves grown under FACE was not caused by the decrease of stomatal conductance.

Acclimatization↗

PubMed2002

[Responses of rice (Oryza sativa) growth and its C, N and P composition to FACE (free-air carbon dioxide enrichment) and N, P fertilization].

FACE (Free-air Carbon Dioxide Enrichment) was used to study the effects of elevated CO2 on rice (Oryza sativa) growth, tissue C/N, N and P concentration and uptake at different development stages under two N and two P levels. Results showed that elevated CO2 increased dry matter accumulation in rice stem, ear and root. Leaf dry matter was increased at tillering stage and no significant effect was found at jointing, heading and ripening stages. N concentration of stem and leaf was decreased. Ear N concentration at heading stage was increased but was decreased at ripening stage. No significant effect was found on root N concentration at tillering stage but root N concentration at jointing, heading and ripening was decreased. Leaf P concentration at jointing, heading and ripening was increased but no significant effect was found on P concentration in stem, ear and root. C content in various tissues changed unremarkably and the ratio of C over N (C/N) was increased. Elevated CO2 significantly increased P uptake in aboveground tissues; and increased N uptake, but the difference was not statistically significant. N and P fertilization had no significant effect on various tissue dry biomass. Tissue N content at higher N fertilization was higher than at lower N fertilization but no such effect of P fertilization on tissue P content was found. At higher N fertilization, elevated CO2 increased the ratio of below-ground biomass over above-ground biomass at ripening stage. Possible reasons are discussed for the differences of tissue N and P content and the ratio of below-ground biomass over above-ground biomass between elevated and ambient atmospheric CO2 concentrations.

Air↗

PubMed2002

[Effect of FACE on competition between a C3 crop (rice, Oryza sativa) and a C4 weed (barnyardgrass, Echinochloa crusgalli)].

The growth and competition of a C3 crop rice and a C4 weed, barnyardgrass under FACE(free-air carbon dioxide enrichment) conditions were studied by field experiment. The results showed that under FACE condition, the biomass and yield, leaf number, tiller number, and leaf area index of rice increased, while those of barnyardgrass decreased. Both of the leaf area indexed of rice and barnyardgrass were decreased, while their net assimilation rate increased. When the ratio of planting density of rice and barnyardgrass was 1:1, all of the ratio of biomass, yield, leaf area index, tiller and net assimilation rate were increased under FACE condition. It indicated that the competition between rice and barnyardgrass changed under FACE condition. The competition ability of rice(C3 crop) was enhanced relatively, while that of barnyardgrass weakened.

Carbon Dioxide↗

PubMed2002

[Rice-wheat rotational FACE platform. I. System structure and control].

A Free Air CO2 Enrichment (FACE) system for rice and winter wheat rotation was established, elevated CO2 concentration was controlled to 200 mumol.mol-1 above ambient by computer system platform according to ambient CO2 concentration variation, wind direction, wind speed, canopy height and day-night changing. Experiments showed that the main factors affecting control precision are wind speed, crop and soil respiration and thickness of diffuse layer. After parameters adjustment, in daytime the time fraction for control precision achieve 80% is 83%, in night is 68%. The CO2 concentrations distribution in FACE rings are uniformity. The set CO2 is 557 mol.mol-1 in daytime and 608 mol.mol-1 in night. In 2001 rice season the target achievement ratios (TAR) were 1.03 after sunrise and 1.09 after sunset, respectively.

Agriculture↗

PubMed2002

[Rice-wheat rotational FACE platform. II. Data processing software package].

A large amount data are brought from daily control, data collection and processing of FACE platform. A FACE system control, data collection and processing software package written in Visual BASIC including OLE to support office functions can finish the platform control, data collection, original data save and backup, daily data processing, monthly data processing and whole time FACE system control status analysis functions, so FACE system controllers can observe FACE system control status and keep control precision timely, and the researchers can get the data they want at any moment and convenient.

Air↗

PubMed2002

Expression of carbonic anhydrase IV in rabbit corneal endothelial cells.

OBJECTIVE: To demonstrate the molecular expression of carbonic anhydrase IV (CA IV) in rabbit corneal endothelium. METHODS: Reverse transcriptase polymerase chain reaction (RT-PCR) was performed using cultured and fresh rabbit corneal endothelial total RNA and specific primers for CA IV. The RT-PCR product was subcloned and sequenced. Immunoblotting and indirect immunofluorescence staining were performed to detect protein expression and distribution of CA IV using fresh and cultured rabbit corneal endothelium and rat anti-CA IV polyclonal antibody. RESULTS: RT-PCR screening gave positive bands at the predicted size for CA IV from fresh and cultured rabbit corneal endothelium. Sequencing further confirmed the identity of CA IV in corneal endothelium. Immunoblotting analysis showed a single band at 52 kDa for freshly isolated and cultured endothelial cells. Indirect immunofluorescence staining revealed an apparent positive staining in cultured endothelial cells. CONCLUSION: Carbonic anhydrase IV is expressed in rabbit corneal endothelium, which could contribute to the transendothelial HCO(3)(-) flux that is necessary to maintain corneal hydration and transparency.

Animals↗

PubMed2002

[Study of the insoluble remainder of human gallstones by scanning electron microscope and Fourier transform infrared spectrum].

The insoluble remainder of brown pigment and mixed gallstones which were dissolved with chloroform, ethanol, ether, and hydrochloric acid were studied by Fourier transform infrared (FT-IR) spectrum and scanning electron microscope. It was found that bilirubinate salts, proteins, fatty salts, phosphate and calcium carbonate are the main components in the insoluble remainder of gallstones. The secondary structure of proteins in brown pigment gallstones may be predominated by alpha-helix. The microstructure of proteins in brown pigment stones is membranous, phosphate and bilirubinate salts were trapped within the membranes. The relationship between the insoluble components and formation of gallstones was discussed.

Bilirubin↗

PubMed2002

Early diagnosis of primary gallbladder carcinoma.

OBJECTIVE: To improve early diagnosis of primary gallbladder carcinoma (PGC) and the understanding of its pathogenesis, pathological stages and prognosis. METHODS: The data from 679 patients with PGC treated in our hospital from 1956 to 1998 were analyzed retrospectively. RESULTS: The incidence of PGC has been increasing in recent years, and the treatment is not satisfactory. Upon diagnosis, most patients with PGC were at advanced stage. PGC was usually found in elderly women. The ratio of man to woman was 1:3. The gallstone, closely related to PGC, was found in 60% of the patients with PGC. The diagnostic accordance rate before and after operation was low. In most patients, PGC was found unexpectedly during operation for gallstone or acute cholecystitis. Many patients with PGC missed the opportunity of diagnosis and therapy because doctor only noticed the diagnosis of gallstone. Pathological classification revealed that PGC in most patients (84.4%) were adenocarcinoma. Imaging helped to find early-stage cases and improve prognosis. CONCLUSIONS: Understanding of pathogenesis, pathological stages and prognosis of PGC and proper use of various examinations are essential to the early diagnosis and treatment of the disease.

Adult↗

PubMed1998

Comparative studies on epithelial lesions at gastric cardia and pyloric antrum in subjects from a high incidence area for esophageal cancer in Henan, China.

AIM:To investigate the pathogenesis of gastric cardia and the distal part of stomach cancer and to further characterize the histopathogenesis model for gastric cardia cancer from the high-risk population for esophageal cancer.METHODS:Mass survey with endoscopic mucosa biopsy and histopathological examination were carried out on 226 subjects aged above 30 years. Three biopsies were collected one each from the middle part of the esophagus, the gastric cardia and the pyloric antrum. The biopsy tissue was fixed with 85% alcohol and paraffin-embedded.RESULTS:The incidence of intestinal metaplasia and dysplasia at gastric cardia epithelium was higher than that at the pyloric antrum from the subjects in the same area. And there were high incidences of both esophageal and gastric cardia cancer, but a low incidence of gastric cancer at the distal part of the stomach.CONCLUSION:There might be different etiology and pathogenesis of gastric cardia and pyloric cancer at the distal part of the stomach.

Journal Article↗

PubMedDate not supplied

RNA aptamers specific for bovine thrombin.

Bovine thrombin is widely used in clinical wound healing after surgery. There is 85% homology between bovine thrombin and human thrombin, so most antibodies against bovine thrombin cross-react with human thrombin. Rare antibodies against bovine thrombin but not cross-reacting with human thrombin have been reported. RNA ligands (aptamers) have been used to bind to target molecules with sometimes higher specificity than antibodies. Here we report the isolation of aptamers specific for bovine thrombin by systematic evolution of ligands by exponential enrichment (SELEX) from an RNA pool containing a 25-nucleotide randomized region. After seven rounds of selection, two aptamers specific for bovine thrombin were identified with a K(d) of 164 and 240 nM, respectively. Significantly, these aptamers do not bind to human thrombin. Secondary structure prediction revealed potential stem-loop structures for these RNAs. Both RNA aptamers inhibit only bovine thrombin-catalyzed fibrin clot formation in vitro. Competition assay results suggested that the RNA aptamers might bind to the electropositive domain of bovine thrombin, that is, heparin-binding site, instead of fibrinogen-recognition exosite. The resulting bovine-specific thrombin inhibitor might be used in some clinical applications when bovine thrombin activity needs to be contained or in research where human and bovine thrombin need to be distinguished.

Animals↗