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Biomedical subjects

Hua Wang

Publications and source records attributed to Hua Wang.

At least 109 records · Page 6Linked to original sources
PubMed2005

Quartz crystal microbalance bioaffinity sensor for biotin based on mixed self-assembled monolayers and metastable molecular complex receptor.

A quartz crystal microbalance (QCM) sensor was proposed for the detection of small molecule biotin based on the mixed self-assembled monolayer (SAM) of thiols on gold substrate and the bioaffinity difference between an analyte (biotin) and an analogue compound (HABA) in binding avidin. Avidin formed a metastable complex with 2-[(4-hydroxyphenyl)azo]benzoic acid (HABA) immobilized on the crystal surface. When the sensor contacts a sample solution containing biotin, the avidin was released from the sensor surface to form a more stable complex with biotin in solution. The frequency change recorded is proportional to the desorbed mass of avidin, and there is a clear mathematic relationship between the frequency change and the biotin concentration. The use of mixed SAMs allows the stable attachment of bioreceptor molecules on the QCM, and enhances the amount of the immobilized molecules on the QCM, as a longer "space arm" in the mixed SAMs makes this monolayer membrane more accessible to capture the immobilized molecules. The proposed bioaffinity sensor has nice response to biotin in the range of 0.017-1.67 microg/mL. The sensor could be regenerated under very mild conditions simply by reimmersion of the sensor into a biotin solution to desorb the surplus avidin.

Azo Compounds↗
PubMed2005

Lipopolysaccharide treatment downregulates the expression of the pregnane X receptor, cyp3a11 and mdr1a genes in mouse placenta.

The cytochrome P450 3A (CYP3A) is a member of the cytochrome P450 monooxygenase superfamily. The multidrug resistance 1 (MDR1) gene belongs to the ATP-binding cassette (ABC) family. Pregnane X receptor (PXR) is a nuclear receptor that regulates its target gene transcription in a ligand-dependent manner. Lipopolysaccharide (LPS)-induced downregulation of PXR, CYP3A and MDR1 in liver has been demonstrated in a series of studies. However, it is not clear whether LPS represses the expression of PXR, CYP3A and MDR1 in placenta. In the present study, we investigated the effects of LPS on the expression of PXR, cyp3a11 and mdr1a in mouse placenta. Pregnant ICR mice were injected intraperitoneally with different doses of LPS (0.1-0.5 mg/kg) on gestational day (gd) 17. Placental PXR, cyp3a11 and mdr1a mRNA levels were determined at 12 h after LPS treatment using RT-PCR. Results showed that LPS significantly downregulated PXR, cyp3a11 and mdr1a mRNA levels in a dose-dependent manner. LPS-induced downregulation of PXR, cyp3a11 and mdr1a mRNA in placenta was significantly attenuated after pregnant mice were pre- and post-treated with alpha-phenyl-N-t-butylnitrone (PBN), a free radical spin trapping agent. Additional experiments revealed that LPS increased lipid peroxidation and proinflammatory cytokine expressions in mouse placenta, all of which were also attenuated by PBN. Furthermore, LPS-induced downregulation of PXR, cyp3a11 and mdr1a mRNA in mouse placenta was prevented by N-acetylcysteine (NAC). NAC also inhibited LPS-initiated lipid peroxidation, GSH depletion and proinflammatory cytokine expressions in mouse placenta. These results indicated that LPS downregulates placental PXR, cyp3a11 and mdr1a mRNA expressions. Reactive oxygen species (ROS) may be involved in LPS-induced downregulation of PXR, cyp3a11 and mdr1a in mouse placenta.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2005

Enzyme-catalyzed amplified immunoassay for the detection of Toxoplasma gondii-specific IgG using Faradaic impedance spectroscopy, CV and QCM.

A highly sensitive electrochemical immunoassay for Toxoplasma gondii-specific IgG (Tg-IgG) in human serum has been developed that is based on an enzyme-catalyzed amplification due to the formation of an insoluble precipitate on the surface of a quartz crystal microbalance (QCM). T. gondii antigen (TgAg) was immobilized on the surface of a gold electrode in order to bind Tg-IgG, and this was followed by the addition of anti-Tg-IgG horseradish peroxidase conjugate (anti-Tg-IgG-HRP). Subsequent exposure to 3,3'-diaminobenzidine (DAB) led to the enzymatically-catalyzed amplified deposition of the oxidation products on the QCM surface in the presence of H2O2. The transduction methods electrochemical Faradaic impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to assay the resistance to electron transfer at the conductive support upon accumulation of the insoluble products. The precipitation process was monitored in real time by QCM. The assay conditions, including the concentration of immobilized TgAg and the dosage of anti-Tg-IgG-HRP conjugate, were optimized. It was found that the amount of precipitate that accumulated on the conductive QCM surface was determined by the concentration of the target analyte Tg-IgG and the time permitted for biocatalyzed precipitation. The technique was shown to give a linear electron transfer resistance response (as measured by EIS) for Tg-IgG dilutions ranging between 1:8000 and 1:200, and a detection limit of 1:9600 dilution.

Animals↗
PubMed2005

The Putative RNA-dependent RNA polymerase RDR6 acts synergistically with ASYMMETRIC LEAVES1 and 2 to repress BREVIPEDICELLUS and MicroRNA165/166 in Arabidopsis leaf development.

The Arabidopsis thaliana ASYMMETRIC LEAVES1 (AS1) and AS2 genes are important for repressing class I KNOTTED1-like homeobox (KNOX) genes and specifying leaf adaxial identity in leaf development. RNA-dependent RNA polymerases (RdRPs) are critical for posttranscriptional and transcriptional gene silencing in eukaryotes; however, very little is known about their functions in plant development. Here, we show that the Arabidopsis RDR6 gene (also called SDE1 and SGS2) that encodes a putative RdRP, together with AS1 and AS2, regulates leaf development. rdr6 single mutant plants displayed only minor phenotypes, whereas rdr6 as1 and rdr6 as2 double mutants showed dramatically enhanced as1 and as2 phenotypes, with severe defects in the leaf adaxial-abaxial polarity and vascular development. In addition, the double mutant plants produced more lobed leaves than the as1 and as2 single mutants and showed leaf-like structures associated on a proportion of leaf blades. The abnormal leaf morphology of the double mutants was accompanied by an extended ectopic expression of a class I KNOX gene BREVIPEDICELLUS (BP) and high levels of microRNA165/166 that may lead to mRNA degradation of genes in the class III HD-ZIP family. Taken together, our data suggest that the Arabidopsis RDR6-associated epigenetic pathway and the AS1-AS2 pathway synergistically repress BP and MIR165/166 for proper plant development.

Arabidopsis↗
PubMed2005

Perinatal lipopolysaccharide exposure downregulates pregnane X receptor and Cyp3a11 expression in fetal mouse liver.

The pregnane X receptor (PXR) is a member of the nuclear receptor superfamily that regulates cytochrome P450 3A (CYP3A) gene transcription in a ligand-dependent manner. Lipopolysaccharide (LPS)-induced downregulation on PXR and cyp3a11 in adult mouse liver has been well characterized. In this study, we investigated the effects of maternal LPS exposure on PXR and cyp3a11 expression in fetal mouse liver. Pregnant ICR mice were injected intraperitoneally with different doses of LPS (0.1 approximately 0.5 mg/kg) on gestational day (GD) 17. PXR and cyp3a11 mRNA levels were determined using RT-PCR. Erythromycin N-demethylase (ERND) activity was used as an indicator of CYP3A expression in this study. Results showed that LPS significantly downregulated PXR and cyp3a11 mRNA levels and ERND activity in fetal liver in a dose-dependent manner. LPS-induced downregulation of PXR and cyp3a11 mRNA expression and ERND activity was attenuated after pregnant mice were pretreated with alpha-phenyl-N-t-butylnitrone (PBN), a free radical spin trapping agent. Additional experiment revealed that LPS significantly increased lipid peroxidation in fetal liver, which was also attenuated by PBN pretreatment. Furthermore, LPS-induced downregulation of PXR and cyp3a11 mRNA expression and ERND activity was prevented by maternal pretreatment with N-acetylcysteine (NAC). Maternal pretreatment with NAC also inhibited LPS-initiated lipid peroxidation and GSH depletion in fetal liver. However, maternal LPS treatment did not affect nitrite plus nitrate concentration in fetal liver. Correspondingly, aminoguanidine, a selective inhibitor of inducible nitric oxide synthase (iNOS), has no effect on LPS-induced downregulation of PXR and cyp3a11 expression and ERND activity in fetal liver. These results indicated that maternal LPS exposure downregulates PXR and cyp3a11 in fetal mouse liver. Reactive oxygen species (ROS) may be involved in LPS-induced downregulation of PXR and cyp3a11 in fetal mouse liver.

Acetylcysteine↗
PubMed2005

[Expression of metabolic enzymes of fluoropyrimidines in primary colorectal cancer and its clinical significance].

OBJECTIVE: To investigate the expression of metabolic enzymes of fluoropyrimidines in primary colorectal cancer. METHODS: Sixty-one cases of pathological confirmed primary colorectal cancer were collected in Beijing Cancer Hospital from August 2003 to February 2004. The expressions of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and orotate phosphoribosyl transferase (OPRT) were detected in paired tumor tissues and non-cancerous tissues by RT-PCR. RESULTS: Expression of each enzyme in tumor tissues was positively correlated with that in paired non-cancerous tissues respectively. Compared with the expression of each enzyme in cancer with that in non-cancer, OPRT was higher in cancer while that of DPD and TS was comparable. The expression of OPRT was approximately 4.38-folds higher in colorectal cancer tissues than that in non-cancerous tissues (P=0.000). The lowest expression of OPRT was found in mucinous carcinoma while the highest levels in poorly-differentiated adenocarcinoma. There were correlations between the ratio of tumor tissues/non-cancerous tissues OPRT expression (T/N) and metastasis to the lymph nodes (r=0.36; P=0.005), small vessel invasion (r=0.26; P=0.041) and differentiation (r=-0.33; P=0.009). CONCLUSION: The detection of three enzymes by means of RT-PCR is practical and can be used in clinical application. Our results also suggest that OPRT is a potential biomarker in predicting prognosis of colorectal cancer.

Adenocarcinoma↗
PubMed2005

[Detection of EWS-WT1 fusion transcripts in paraffin-embedded tissues for desmoplastic small round cell tumor].

OBJECTIVE: To detect the EWS-WT1 chimeric mRNA in desmoplastic small round cell tumor (DSRCT) and its clinicopathological significance. METHODS: Formalin fixed, paraffin-embedded tumor specimens from 4 examples of this entity were studied by reverse transcriptase polymerase chain reaction to detect the EWS-WT1 fusion transcripts resulting from the chromosomal translocation t(11;22)(p13;q12). The following tumor specimens were included as controls: 2 Ewing's sarcomas/primitive neuroectodermal tumors (PNET/ES), 2 alveolar rhabdomyosarcomas, and 2 lymphomas. RESULTS: EWS-WT1 fusion transcripts were detected in 3 of 4 desmoplastic small round cell tumors but not in any other tumor types studied as controls. CONCLUSION: The analysis of the EWS-WT1 fusion transcript which was performed on formalin-fixed, paraffin-embedded tissues is a sensitive and specific method in the diagnosis and differential diagnosis of DSRCT.

Abdominal Neoplasms↗
PubMed2005

Research progress on Helicobacter pylori outer membrane protein.

Helicobacter pylori (H pylori), one of the most common bacterial pathogens on human beings, colonizes the gastric mucosa. In its 95 paralogous gene families, there is a large outer membrane protein (OMP) family. It includes 32 members. These OMP are important for the diagnosis, protective immunity, pathogenicity of H pylori and so on. They are significantly associated with high H pylori density, the damage of gastric mucosa, high mucosal IL-8 levels and severe neutrophil infiltration. We introduce their research progress on pathogenicity.

Bacterial Outer Membrane Proteins↗
PubMed2005

Protective effect of fufanghuangqiduogan against acute liver injury in mice.

AIM: To study the effects and possible mechanisms of fufanghuangqiduogan (FFHQ) in mice with acute liver injury (ALI). METHODS: ALI was successfully induced by injecting carbon tetrachloride (CCl4) intraperitoneally and by tail vein injection of Bacillus Calmette Guerin (BCG) and lipopolysaccharide (LPS) in mice, respectively. Each of the two model groups was divided into normal group, model group, FFHQ (60, 120 and 240 mg/kg) treatment groups, and bifendate treatment group. At the end of the experiment, levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), content of malondialdehyde (MDA), activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) in liver homogenate were measured by biochemical methods. The activities of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) were determined by radio-immunoassay. Hepatic tissue sections were stained with hematoxylin and eosin and examined under a light microscope. RESULTS: In the two models of ALI, FFHQ (60, 120, 240 mg/kg) was found to significantly decrease the serum transaminase (ALT, AST) activities. Meanwhile, FFHQ decreased MDA contents and upregulated the lower SOD and GSH-px levels in liver homogenate. Furthermore, in immunologic liver injury model, FFHQ decreased levels of TNF-alpha and IL-1 in serum. Histologic examination showed that FFHQ could attenuate the area and extent of necrosis, reduce the immigration of inflammatory cells. CONCLUSION: FFHQ had protective effect on liver injury induced by either CCl4 or BCG+LPS in mice, and its mechanisms were related to free radical scavenging, increasing SOD and GSH-px activities and inhibiting the production of proinflammatory mediators.

Acute Disease↗
PubMed2005

Nanogold particle-enhanced oriented adsorption of antibody fragments for immunosensing platforms.

A general design strategy for immunosensing platforms has been proposed on the basis of Nanogold particle-enhanced oriented adsorption of antibody fragments. Quartz crystal microbalance (QCM) as a model transducer was fabricated with plasma-polymerized film (PPF) of n-butyl amine and then with nanogold particles resulting in a PPF-nanogold adsorption procedure for half-IgG fragments obtained by reduction of intact immunoglobulin (IgG). Thermodynamic studies reveal that the proposed procedure is superior to the traditional oriented ones in that it created immunosurface of increased antibody surface density (amount) and antigen binding constants. Sensors produced according to the new immobilization procedure exhibit better immunosensing performances including high sensitivity, fast response rate, and favorable operational stability etc. This Nanogold particle-enhanced immobilization technique may be tailored as a promising alternative for various immunosensing platforms in solid-phase immunoassay and affinity chromatography.

Adsorption↗
PubMed2005

Effects of transforming growth factor beta 1 on the growth of rhabdomyosarcoma cell line RD.

BACKGROUND: Transforming growth factor-beta (TGF-beta) can inhibit the growth of most epithelial and endothelial cells. The growth regulative role of TGF-beta on soft tissue sarcoma was seldom reported. Here we examined TGF-beta1 effects on the growth of human rhabdomyosarcoma cell RD and searched the relative molecular mechanism. METHODS: The viability of RD was examined by [(3)H]-thymidine incorporation and [3-(4,5-dimethylthiazol-z-yl)-2,5-diphenyl tetrazolium bromide] (MTT) assay. RD cell cycle was analysed by flow cytometry. The protein and mRNA of cell cycle regulative factors in RD were detected by Western blot and reverse transcription-polymerase chain reaction (RT-PCR), respectively. The kinase activity of cdk2 or cdk4 was examined by immunoprecipitation and kinase assay. Immunofluorescent staining was used to detect the location of cell cycle regulative factors in RD by laser scanning confocal microscope. RESULTS: TGF-beta1 inhibits RD proliferation by G1-arrest in cell cycle progression. TGF-beta1 can prominently up-regulate P27 of RD, then augment P27 to bind cyclinE-cdk2 complexes, which effectively suppress cdk2 kinase activity. P21 increased and c-myc decreased in RD due to TGF-beta1. Both P15 and cdk4 have not been involved in the growth inhibitory event. TGF-beta1 treatment induced P27 to congregate around nucleus. P21 pervaded from nucleus to both nucleus and cytoplasm by TGF-beta1 treatment. CONCLUSION: TGF-beta1 inhibits the proliferation of human rhabdomyosarcoma cell line RD and induces RD G1-arrest. This course is accomplished by TGF-beta1 up-regulating P27 to suppress cdk2 kinase activity. The induction of P21 and down-regulation of C-myc might participate in the growth-arrest event.

Cell Cycle Proteins↗
PubMed2005

Effects of total glucosides of peony on immunological hepatic fibrosis in rats.

AIM: To study the effects of total glucosides of peony (TGP) on immunological hepatic fibrosis induced by human albumin in rats. METHODS: Sixty adult male Sprague-Dawley rats were randomly divided into: Normal group, model group, TGP (60 and 120 mg/kg) treatment groups and colchicines (0.1 mg/kg) treatment group. On the day before the rats were killed, those in TGP or colchicine groups received TGP or colchicine as above from the first day of tail vein injection of human albumin. The rats in normal and model groups were only administered with the same volume of vehicle. At the end of the 16th wk, rats in each group were killed. Blood and tissue specimens were taken. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO), content of malondialdehyde (MDA), activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px), were measured by biochemical methods. Serum procollagen type III (PC III) and laminin (LN) were determined by radioimmunoassay. Liver collagen level was determined by measuring hydroxyproline content in fresh liver samples. Hepatic tissue sections were stained with hematoxylin-eosin and examined under a light microscope. RESULTS: Histological results showed that TGP improved the human albumin-induced alterations in the liver structure, alleviated lobular necrosis and significantly lowered collagen content. The antifibrotic effect of TGP was also confirmed by decreased serum content of LN and PCIII in TGP-treated group. Moreover, the treatment with TGP effectively reduced the hydroxyproline content in liver homogenates. However, the level of ALT and AST increased in fibrotic rat but had no significance compared with normal control, whereas the ratio of A/G decreased without significance. TGP had no effect on level of ALT, AST and the ratio of A/G. Furthermore, TGP treatment significantly blocked the increase in MDA and NO, associated with a partial elevation in liver total antioxidant capacity including SOD and GSH-px. CONCLUSION: TGP has beneficial effects on hepatic fibrosis in rats by inhibition of collagen synthesis and decreasing oxidative stress.

Animals↗
PubMed2005

A small interfering RNA targeting vascular endothelial growth factor inhibits Ewing's sarcoma growth in a xenograft mouse model.

Angiogenesis plays an essential role in tumor growth and metastasis and is a promising therapeutic target for cancer. Vascular endothelial growth factor (VEGF) is a key regulator in vasculogenesis as well as in angiogenesis. TC71 human Ewing's sarcoma cells overexpress VEGF, with a shift in isoform production from membrane-bound VEGF189 to the more soluble VEGF165. Transfection of TC71 cells with a vector-based VEGF targeted small interfering RNA expression system (VEGFsi) inhibited VEGF165 expression by 80% and VEGF165 protein production by 98%, with no alteration in VEGF189 expression. Human microvascular endothelial cell proliferation and migration induced by conditioned medium from VEGFsi-transfected TC71 cells was significantly less than that induced by conditioned medium from TC71 cells and control vector-transfected TC71 cells. Furthermore, after s.c. injection into athymic nu/nu mice, the tumor growth of VEGFsi-expressing TC71 cells was significantly less than that of parental or control vector-transfected cells. Vessel density as assessed by CD31 immunohistochemical analysis and VEGF165 expression as assessed by Northern blotting were also decreased. Intratumor gene therapy with polyethylenimine/VEGFsi also resulted in tumor growth suppression. When inoculated into the tibias of nude mice, VEGFsi-expressing TC71 cells induced osteolytic bone lesions that were less severe than those induced by control groups. These data suggest that targeting VEGF165 may provide a therapeutic option for Ewing's sarcoma.

Animals↗
PubMed2005

Improved method for the preparation of carboxylic acid and amine terminated self-assembled monolayers of alkanethiolates.

We present an improved method to prepare carboxylic acid (COOH) and amine (NH2) terminated self-assembled monolayers (SAMs) of alkanethiolates. In this method, a small amount of CF3COOH (for COOH-SAM) or N(CH2CH3)3 (for NH2-SAM) is added into the ethanolic solution of alkanethiols during SAM formation. The freshly formed COOH- and NH2-SAMs are then rinsed with an ethanolic solution of NH4OH or CH3COOH, respectively. Both SAMs prepared with the improved method show better quality in terms of surface chemical composition, roughness, and wettability as measured by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle, respectively. The formation of better SAMs can be attributed to the disruption of interplane hydrogen bonds.

Alkanes↗
PubMed2005

A velocity map ion-imaging study on ketene photodissociation at 208 and 213 nm: Rotational dependence of product angular anisotropy.

Photodissociation dynamics of ketene following excitation at 208.59 and 213.24 nm have been investigated using the velocity map ion-imaging method. Both the angular distribution and translational energy distribution of the CO products at different rotational and vibrational states have been obtained. No significant difference in the translational energy distributions for different CO rotational state products has been observed at both excitation wavelengths. The anisotropy parameter beta is, however, noticeably different for different CO rotational state products at both excitation wavelengths. For lower rotational states of the CO product, beta is smaller than zero, while beta is larger than zero for CO at higher rotational states. The observed rotational dependence of angular anisotropy is interpreted as the dynamical influence of a peculiar conical intersection between the (1)B(1) excited state and (1)A(2) state along the C(S)-I coordinate.

Journal Article↗
PubMed2005

The androgen receptor directly targets the cellular Fas/FasL-associated death domain protein-like inhibitory protein gene to promote the androgen-independent growth of prostate cancer cells.

Androgens provide survival signals to prostate epithelial cells, and androgen ablation induces apoptosis in the prostate gland. However, the molecular mechanisms of actions of the androgen-signaling pathway in these processes are not fully understood. Here, we report that androgens induced expression of the cellular Fas/FasL-associated death domain protein-like inhibitory protein (c-FLIP) gene, which is a potent inhibitor of Fas/FasL-mediated apoptosis. The androgen receptor was recruited to the promoter of the c-FLIP gene in the presence of androgens. We found that c-FLIP promoter contained multiple functional androgen response elements. In addition, we show that c-FLIP overexpression accelerated progression to androgen independence by inhibiting apoptosis in LNCaP prostate tumors implanted in nude mice. Our results suggest that the androgen receptor affects survival and apoptosis of prostate cells through regulation of the c-FLIP gene in response to androgens.

Androgens↗
PubMed2005

[Screening for congenital hypothyroidism in 106 224 neonates in Hunan Province].

OBJECTIVE: Diagnosing congenital hypothyroidism (CH) early was studied in this paper through neonatal screening to prevent children's mental retardation. METHODS: The first step is mensurating the concentration of thyroid stimulating hormone (TSH) with the method of time-distinguished fluorometry immunoassay. If the result is positive, then it is necessary to mensurate the serum TSH, free triiodothyronine (FT3),free thyroxin (FT4) with chemiluminescence immunoassay (CLIA) and execute clinical diagnosis. RESULTS: There were 68 confirmed congenital hypothyroidism patients among the 106,224 samples from Apr.1997 to Dec.2003 in Hunan province. The positive rate was 1/1,562, which was obviously higher than the national average value (1/3,009). CONCLUSION: First, neonatal screening is the key to prevent mental retardation through early diagnosing and treating CH. Second, the probability of suffering CH is high in Hunan province. Third, the positive rate is relative to the development of science and technology, while the accumulated rate is better to reflect the real incidence of the disease. Fourth, selecting proper critical value will help to prevent missing screening.

China↗