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Biomedical subjects

G Wang

Publications and source records attributed to G Wang.

At least 271 records · Page 15Linked to original sources
PubMed2000

Human SP-A protein variants derived from one or both genes stimulate TNF-alpha production in the THP-1 cell line.

In humans, two functional genes of surfactant protein (SP) A, SP-A1 and SP-A2, and several alleles of each functional gene have been characterized. SP-A is a multimeric molecule consisting of six trimers. Each trimer contains two SP-A1 molecules and one SP-A2 molecule. Until now, it has been unclear whether a single SP-A gene product is functional or whether there are functional differences either among alleles or between single-gene SP-A products and SP-A products derived from both genes. We tested the ability of in vitro expressed SP-A variants to stimulate tumor necrosis factor (TNF)-alpha production by THP-1 cells. We observed that 1) single-gene products and products derived from both genes stimulate TNF-alpha production, 2) there are differences among SP-A1 and SP-A2 alleles in their ability to stimulate TNF-alpha production, and 3) the increases in TNF-alpha production are lower after treatment with the SP-A1 alleles than after treatment with the SP-A2 alleles. Furthermore, coexpressed SP-As from SP-A1 and SP-A2 genes have a higher activity compared with SP-As from individual alleles or mixed SP-As from SP-A1 and SP-A2 genes. These data suggest that the SP-A-induced increases in TNF-alpha levels differ among SP-A variants and appear to be affected by SP-A genotype and whether SP-A is derived from one or both genes.

Alleles↗
PubMed2000

Increasing epithelial junction permeability enhances gene transfer to airway epithelia In vivo.

Gene transfer to airway epithelia is the most direct approach for treating the progressive lung disease associated with cystic fibrosis. However, the transduction efficiency is poor when viral vectors are applied to the mucosal surface. We reported previously that gene transfer via the apical surface of human airway epithelia in vitro was improved by formulating vectors with ethyleneglycol-bis-(2-aminoethyl ether)- N,N,N',N'-tetraacetic acid (EGTA) in a hypotonic buffer. First, we investigated the mechanism for this enhancement. When 100-nm fluorescent beads were applied to the apical surface in the presence of EGTA, paracellular deposition of the particles was noted. Transmission electron microscopy verified that the epithelial junction complex was disrupted under these conditions. The Ca(2+) chelators EGTA, 1,2-bis (2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA), and ethylenediaminetetraacetic acid all caused a rapid, reversible drop in transepithelial resistance and facilitated gene transfer with retrovirus or adenovirus in vitro. When Ca(2+) chelators were applied to rabbit tracheal epithelia or human nasal epithelia in vivo, the transepithelial voltage decreased, and amiloride sensitivity was lost, suggesting that epithelial junctions opened. Importantly, this novel formulation enhanced both retroviral- and adenoviral-mediated gene transfer to rabbit tracheal epithelia in vivo. This technique may have applications for vector or drug delivery to airway epithelia and other polarized cells.

Amiloride↗
PubMed2000

Regulation of tumor cell apoptotic sensitivity during the cell cycle (Review).

Understanding how current chemotherapeutic modalities induce apoptosis is critical to designing better anti-cancer agents. This review is concerned with how pharmacological agents induce tumor cell apoptosis in a cell cycle-dependent manner. Recent experiments demonstrate that expression of several apoptotic regulatory proteins (such as Bcl-2, Bax, p53, and Survivin) are differentially regulated according to the phases of the cell cycle. This cell cycle-dependent regulation in turn contributes to increased drug sensitivity in different phases of the cell cycle. It is therefore likely that the cell cycle-dependent expression of cell death proteins plays a role in regulating chemosensitivity and apoptotic commitment of human tumor cells.

Antineoplastic Agents↗
PubMed2000

Effect of dietary fatty acids on tumorigenesis of colon cancer induced by methyl nitrosourea in rats.

We studied the effect of dietary fatty acid composition on the tumorigenesis of colon cancer induced by methyl nitrosourea (MNU) in rats. Five groups of Sprague-Dawley male rats were fed with semi-synthetic diets that contained different proportions of beef tallow, soybean oil, alkana oil, corn oil, and fish oil for 180 days. Each group was matched with a control group fed with the same diet. The experimental groups were given MNU in PBS i.p. 6 times at weekly intervals. The control groups were given PBS only. The incidence of colon cancer, the average volume of the tumors, PCNA, cell kinetics, membrane lipid fluidity, ALP activity, and the content of PGE2 in colonic mucous and the fatty acid distribution in the testis pad fat were measured at the end of the experiment. The results showed that the incidence of colon cancer and the average volume of the tumors in animals fed with diets that contained mainly beef tallow, soybean oil, or alkana oil were significantly higher than that in animals fed with diets that contained mainly fish oil. The diet containing 13.9% of SFA, 16.4% of MUFA, and 68.8% of PUFA showed the strongest inhibition effect. This may be due to the mechanism of protecting the membrane lipid fluidity, decreasing the amount of PCNA in colon cells, the number of propidium iodine-labeled cells in S phase, the activity of ALP and inhibiting the production of AA and thus decreasing the amount of PGE2.

Alkaline Phosphatase↗
PubMed2000

[Association between hypertensive cerebrovascular stroke and renin-angiotensin system gene polymorphism from Chinese cohort in Shanghai].

OBJECTIVE: To evaluate the association between hypertensive cerebrovascular stroke and renin-angiotensin system gene polymorphism from Chinese cohort. METHODS: The polymorphisms of angiotensinogen(AGT) and angiotensin-converting enzyme(ACE) from 257 cases of simple essential hypertension(EH) and 218 cases of hypertensive stroke(131 hemorrhagic cases and 87 ischemic cases were detected by PCR-RFLP. RESULTS: The frequencies of DD genotype and D allele of ACE gene in ischemic stroke were significantly higher than those in hemorrhagic stroke and EH, and the odds ratios(OR) of DD/II genotype were 3.25(2.20-4.79) and 2.87(2.03-4.06), while the OR of D/I allele were 1.83(1.38-2.43) and 1.69(1.27-2.24) respectively. Otherwise, there was no difference in frequency distribution of Met235Thr mutation polymorphism and DD+TT/non DD non TT combined among the three groups. CONCLUSION: The I/D polymorphism of ACE gene may be one of the risk factors and susceptible genetic markers for ischemic stroke with essential hypertension in Chinese.

Angiotensinogen↗
PubMed2000

Secretory response of endothelin-1 in cultured human glomerular microvascular endothelial cells to shear stress.

The shear-induced secretory response of endothelin-1 (ET-1) by human microvascular endothelial cells was studied using paired human glomerular microvascular endothelial cell (HGMEC) cultured monolayers exposed to steady-state laminar shear stress for up to 10 hours. The first cell monolayer was subjected to a shear stress of 0.65 N m-2 and the second, 1.3 N m-2. ET-1 secretion was determined by radioimmunoassay. Over 10 hours of shear, the total cumulative secretion of ET-1 was 237.4 pg/cm2 for the monolayer exposed to 1.3 N m-2 and 143.6 pg/cm2 for the monolayer exposed to 0.65 N m-2. The average ET-1 secretion rate was 20.90 +/- 2.15 and 12.45 +/- 1.05 pg/cm2.h at 0.65 N m-2 and 1.3 N m-2, respectively. The results showed that ET-1 secretion varied with the time of shear in a nonlinear fashion. Although the level of shear stress affected the absolute value of ET-1 cumulative secretion and secretion rate, the major secretion period for both monolayers occurred between 2.0 and 8.0 hours, with the peak secretion rate occurring at approximately 5 hours. Thus, the response of cultured human microvascular endothelial cells to shear stress differed from that of large vessel endothelial cell cultures in terms of ET-1 secretion. In addition to the level of shear stress, the time of shear was also an important determinant of ET-1 secretion. Consequently, the heterogeneity of vascular endothelial cells and the time of shear should both be considered in future research on the secretion of vascular endothelial cell cultures.

Capillaries↗
PubMed2000

Development of retroviral vectors for gene transfer to airway epithelia.

Retroviral vectors offer several potential advantages for attaining persistent expression of a therapeutic gene in airway epithelia for diseases such as cystic fibrosis. However, several problems have limited their application. Developments in vector production and the advent of lentiviral vectors have increased the investigation of recombinant retrovirus for gene transfer to airway epithelia. In addition, an improved understanding of some of the barriers limiting gene transfer has led to increased transduction efficiencies. The development of novel vector formulations and the use of new envelope pseudotypes are examples of recent findings that are leading to advances in this field.

Animals↗
PubMed2000

Characterizations of three surface-modified titanium oxide films.

OBJECTIVE: To seek a new method of titanium passive treatment by combined anodic oxidation and thermal air treatment, which could increase the corrosion resistance and biocompatibility of pure titanium. MATERIAL AND METHODS: Characteristics of Titanium sheets with natural oxide film (NOF), anodic oxide film (AOF), or heated anodic oxide film (HAOF) were compared and tested by x-ray diffractrometer, electrochemical corrosive method, and contact angle device. RESULTS: HAOF had excellent corrosion resistance and greater crystallinity, indicating the crystal structure had changed. AOF had better hydrophily. CONCLUSION: This in vitro study showed that thermal air treatment, after anodic oxidation, was a reliable method for creating a passive, protective film on the titanium surface, which could greatly enhance the corrosion-resistance and crystallinity.

Air↗
PubMed2000

[Effect of hypoxia and carbon monoxide on rat pulmonary arterial smooth muscle cell].

OBJECTIVE: To investigate the effect of carbon monoxide on rat pulmonary arterial smooth muscle cell (VSMC). METHODS: Three groups were randomly divided, (1) Normoxia group(N), (2) Hypoxia group(H), (3) 3% CO + 1% O2 group (CO + H), then tested by immunocytochemical analysis 3H-TdR in incorporation. RESULTS: (1) Hypoxia initiated the chang of VSMC from contractile phenotype to synthetic phenotype, the endoplasmic reticulum became dilated, the mitochondria became swollen and myelin figure appeared. alpha-actin and muscle fiber decreased. The form of VSMC in CO + H was similar to that in N. (2) Intracellular Ca2+ level of VSMC in H [4 h, 8 h, 12 h, 24 h, 36 h were (382.00 +/- 37.92) mmol/L, (456.00 +/- 53.76) mmol/L, (517.00 +/- 47.34) mmol/L, (608.00 +/- 35.92) mmol/L, (567.00 +/- 46.72) mmol/L, respectively] increased significantly(P < 0.01) than in N[4 h was(319.00 +/- 47.45) mmol/L], but that in CO + H increased slightly. (3) cAMP and cGMP level of VSMC in H increased significantly, cAMP of VSMC in CO + H increased significantly [2 h, 8 h, 12 h, 24 h were (1.87 +/- 0.36) pmol/mg protein, (2.16 +/- 0.36) pmol/mg protein, (2.36 +/- 0.41) pmol/mg protein, (2.12 +/- 0.39) pmol/mg protein, respectively] but cGMP of VSMC in CO + H increased slightly[2 h, 8 h, 12 h, 24 h were (0.52 +/- 0.21) pmol/mg protein, (0.58 +/- 0.21) pmol/mg protein, (0.60 +/- 0.24) pmol/mg protein, (0.68 +/- 0.29) pmol/mg protein, respectively]. CONCLUSION: Hypoxia may promote the proliferation of VSMC by second messenger system and CO in low desities can depress the action of hypoxia partly by Ca(2+)-cGMP system or by the expression of E2F-1 gene.

Animals↗
PubMed2000

[Factors affecting transformation of Agrobacterium tumefaciens and their application on cereals].

Agrobacterium tumefaciens mediated genetic transformation is the method most widely used in plant transformation. How to improve its transformation efficiency and extend its host range to include most cereals is what people concern about. There are many factors that influence the transformation efficiency, including the wounding response of plants, attachment of bacteria, induction of virulent gene, DNA repair and replication activity of plant cells, state of explant, etc. Recent research has proved that cerelas can be transformed effectively by A. tumefaciens under suitable conditions. This paper reviewed the recent progress in the two aspects.

Agrobacterium tumefaciens↗
PubMed2000

[Effect of osmotic stress on wheat membrane injury under different CO2 concentrations].

This paper studied the variation of active oxygen content and membrane permeability in leaves of spring wheat seedling exposed to osmotic stress under normal 350 microliters.L-1 and doubled CO2 concentration 700 microliters.L-1. The results indicate that the increasing rate of O2.- and H2O2, and the membrane permeability in wheat leaves exposed to osmotic stress in normal CO2 concentration were higher than those in doubled CO2. Accordingly, it is suggested that doubled CO2 can reduce the membrane oxidative injury caused by osmotic stress, and increase plant drought resistance.

Carbon Dioxide↗
PubMed2000

[Effect of elevated CO2 concentration on photosynthesis and antioxidative enzyme activities of wheat plant grown under drought condition].

The photosynthesis and antioxidative enzyme activities of wheat plants grown in two open-top chambers with CO2 concentrations of 350 mumol.mol-1 and 700 mumol.mol-1 were examined under drought stress. The result showed that elevated CO2 concentration obviously enhanced the photosynthesis, stomatal resistance and water use efficiency, but decreased the transpiration of wheat. Doubled CO2 concentration significantly increased the activities of CAT, POD and SOD, which enhanced the abilities of antioxidative defence and drought tolerance.

Carbon Dioxide↗
PubMed2000

[Grey system analysis on dominant natural enemies influencing Aphis gosspyii population].

The populations of Aphis gosspyii and its natural enemies before cotton boll stage were investigated systematically in 1983, 1984, 1986, 1988, 1994 and 1995. The relationship between daily total predation of natural enemies and Aphis gosspyii population size was studied with the grey system theory and method, and the relational grade of various natural enemies to ideal superior natural enemies was analyzed. The results show that Propylaca japonica was the major natural enemy influencing Aphis gossypii, followed by Chrysopa septempunctata, then by Therdion octomaculatum and Erigonidium graminicola.

Animals↗
PubMed2000

[Geostatistical analysis on spatial patterns of Aphis gossypii and Propylaca japonica].

The spatial construction and distribution of Aphis gossypii and Propylaca japonica at different period were investigated with geostatistics. The results showed that the semivariogram of Aphis gossypii was described by spherical model, indicating an aggregated spatial arrangement, the range was 8.21-10.81 m. The semivariograms of Propylaca japonica was fitted by spherical model too, also indicating an aggregated spatial arrangement, its range was 8.01-14.25 m. The amount and spatial distribution of Propylaca japonica was closely related to that of Aphis gossypii. It reveals that Propylaca japonica is dominant natural enemies of influencing population of Ahphis gossypii.

Animals↗
PubMed2000

Enhanced oxidant stress in synovial vessels of patients on hemodialysis.

OBJECTIVE: To test the hypothesis that the susceptibility of synovial vessels to redox uncoupling which could result in oxidative damage capable of promoting beta 2-microglobulin (beta 2 m) deposition. METHODS: The expression of oxidative markers by microvascular endothelial cells in hemodialysis (HD) patients, non-uremic patients and normal subjects was determined using immunostaining and Northern blotting. RESULTS: Synovial vascular endothelial cells of HD patients exhibited evidence of oxidant stress: induction of malondialdehyde (MDA) epitopes and heme oxygenase. These oxidative markers were not detectable in microvascular endothelial cells of other tissues from HD patients, as well as in the synovial vessels of non-uremic or normal controls. Higher levels of heme oxygenase mRNA in synovia were seen in patients with beta 2 m deposition compared with patients without beta 2 m deposition. CONCLUSIONS: Oxidative damage of the synovial microvasculature in uremic patients may be one of the factors which can promote deposition of beta 2 m in osteoarticular tissue.

Adult↗
PubMed2000

Oxidized low density lipoprotein inhibited tissue factor pathway inhibitor mRNA expression in human endothelial cells.

OBJECTIVE: To understand the role of oxidized low density lipoprotein (OX-LDL) in the pathogenesis of thrombotic complications in atherogenesis. METHODS: Low density lipoprotein was isolated from normal heparinized blood by density gradient ultracentrifugation and oxidized by CuCl2. Total RNA was extracted from human umbilical vein endothelial cells (HUVECs) exposed to LDL or OX-LDL, using the guanidinium isothiocyanate method. The quantification of tissue factor pathway inhibitor (TFPI) mRNA in HUVECs was carried out by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: HUVECs were able to express TFPI mRNA constitutively. The expression was not affected by LDL but was effectively inhibited by OX-LDL in a time- and dose-dependent manner. CONCLUSIONS: The results suggest that oxidized LDL may play an important role in inducing coagulation in atherosclerotic lesions by the inhibition of expression of TFPI in vascular endothelial cells.

Endothelium, Vascular↗