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Biomedical subjects

Yan Wang

Publications and source records attributed to Yan Wang.

At least 271 records · Page 15Linked to original sources
PubMed2005

Biochemical characterization and vaccine potential of a heme-binding glutathione transferase from the adult hookworm Ancylostoma caninum.

We report the cloning and expression of Ac-GST-1, a novel glutathione S-transferase from the adult hookworm Ancylostoma caninum, and its possible role in parasite blood feeding and as a vaccine target. The predicted Ac-GST-1 open reading frame contains 207 amino acids (mass, 24 kDa) and exhibited up to 65% amino acid identity with other nematode GSTs. mRNA encoding Ac-GST-1 was detected in adults, eggs, and larval stages, but the protein was detected only in adult hookworm somatic extracts and excretory/secretory products. Using antiserum to the recombinant protein, Ac-GST-1 was immunolocalized to the parasite hypodermis and muscle tissue and weakly to the intestine. Recombinant Ac-GST-1 was enzymatically active, as determined by conjugation of glutathione to a model substrate, and exhibited a novel high-affinity binding site for hematin. The possible role of Ac-GST-1 in parasite heme detoxification during hemoglobin digestion or heme uptake prompted interest in evaluating it as a potential vaccine antigen. Vaccination of dogs with Ac-GST-1 resulted in a 39.4% reduction in the mean worm burden and 32.3% reduction in egg counts compared to control dogs following larval challenge, although the reductions were not statistically significant. However, hamsters vaccinated with Ac-GST-1 exhibited statistically significant worm reduction (53.7%) following challenge with heterologous Necator americanus larvae. These studies suggest that Ac-GST-1 is a possible drug and vaccine target for hookworm infection.

Amino Acid Sequence↗
PubMed2005

Inhibition of insulin-like growth factor-I receptor (IGF-IR) signaling and tumor cell growth by a fully human neutralizing anti-IGF-IR antibody.

Insulin-like growth factor-I receptor (IGF-IR) plays an important role in tumor cell growth and survival. On ligand stimulation, IGF-IR, a receptor tyrosine kinase, phosphorylates tyrosine residues on two major substrates, IRS-1 and Shc, which subsequently signal through the Ras/mitogen-activated protein kinase and phosphatidylinositol 3-kinase/AKT pathways. Here, we describe the characterization of a fully human anti-IGF-IR monoclonal antibody 19D12 that inhibits IGF binding and autophosphorylation of both IGF-IR/IGF-IR homodimers and IGF-IR/insulin receptor heterodimers. 19D12 does not recognize insulin receptor homodimers. In addition to inhibiting IGF-IR autophosphorylation, 19D12 also inhibits IRS-1 phosphorylation and activation of the major downstream signaling molecules AKT and extracellular signal-regulated kinase 1/2. Furthermore, the antibody down-regulates the total IGF-IR protein level and can exhibit antibody-dependent cellular cytotoxicity activity against a non-small cell adenocarcinoma cell line in vitro in the presence of isolated human natural killer cells. 19D12 binds tightly to the receptor, with an affinity of 3.8 pmol/L as measured by KinExA. In cell culture, 19D12 inhibits proliferation and soft agar growth of various tumor cell lines. In vivo, 19D12 inhibits the tumor growth of a very aggressive human ovarian tumor xenograft model A2780. These data support the development of this anti-IGF-IR monoclonal antibody as a promising anticancer agent.

Animals↗
PubMed2005

Age-dependent morphine tolerance development in the rat.

In all age groups, the use of opioids to treat chronic pain conditions has increased, yet the impact of age on opioid tolerance development has not been comprehensively addressed. In this study, we investigated age-related differences in morphine tolerance development in rats. Rats aged 3 wk, 3 mo, 6 mo, and 1 yr were used in the study. Morphine (8 mg/kg) was injected subcutaneously twice each day and its analgesic effect assessed by the change in tail-flick latency using a thermal stimulus 5 min before and 30 min after dosing. Tolerance was defined as a 75% reduction in morphine-induced analgesia compared to Day 1. Rats aged 3 wk, 3 mo, 6 mo, and 1 yr developed tolerance on the 4th, 10th, 14th, and 22nd days of morphine treatment, respectively. Plasma levels of morphine and its metabolites showed that pharmacokinetic differences among the groups did not correlate with the differences in tolerance development. This study demonstrates that morphine tolerance occurs more rapidly in younger rats than older rats and is unlikely to be the result of differences in drug metabolism or clearance. Aging may impact molecular processes involved in tolerance development and provide insight into novel therapeutic targets to delay opioid tolerance development.

Aging↗
PubMed2005

In vitro antifungal activity of ZJ-522, a new triazole restructured from fluconazole and butenafine, against clinically important fungi in comparison with fluconazole and butenafine.

The antifungal activity of ZJ-522, a new triazole antifungal agent restructured from fluconazole and butenafine, was compared to that of fluconazole and butenafine against 43 strains of fungi representing 13 fungal species. MICs were determined by using the National Committee for Clinical Laboratory Standards (NCCLS)-recommended broth microdilution method for yeasts, which was modified for filamentous fungi. ZJ-522 was about 50-fold and 2 to 16-fold more potent than fluconazole against yeasts and filamentous fungi respectively, but it was less active than butenafine against filamentous fungi, although butenafine was inactive against most yeasts. Thus, the fashion of ZJ-522 antifungal activity more similar to that of fluconazole than that of butenafine indicates that ZJ-522 should be an inhibitor of lanosterol 14alpha-demethylase but not of squalene epoxidase, and should be a candidate for clinical development.

Antifungal Agents↗
PubMed2005

In vitro and in vivo antifungal activities of the eight steroid saponins from Tribulus terrestris L. with potent activity against fluconazole-resistant fungal pathogens.

Antifungal activity of natural products is being studied widely. Saponins are known to be antifungal and antibacterial. We have isolated eight steroid saponins from Tribulus terrestris L., namely TTS-8, TTS-9, TTS-10, TTS-11, TTS-12, TTS-13, TTS-14 and TTS-15. TTS-12 and TTS-15 were identified as tigogenin-3-O-beta-D-xylopyranosyl(1-->2)-[beta-D-xylopyranosyl(1-->3)]-beta-D-glucopyranosyl(1-->4)-[alpha-L-rhamnopyranosyl(1-->2)]-beta-D-galactopyranoside and tigogenin-3-O-beta-D-glucopyranosyl(1-->2)-[beta-D-xylopyranosyl(1-->3)]-beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside, respectively. The in vitro antifungal activities of the eight saponins against six fluconazole-resistant yeasts, Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, Candida krusei, and Cryptococcus neoformans were studied using microbroth dilution assay. The results showed that TTS-12 and TTS-15 were very effective against several pathogenic candidal species and C. neoformans in vitro. It is noteworthy that TTS-12 and TTS-15 were very active against fluconazole-resistant C. albicans (MIC(80)=4.4, 9.4 microg/ml), C. neoformans (MIC(80)=10.7, 18.7 microg/ml) and inherently resistant C. krusei (MIC(80)=8.8, 18.4 microg/ml). So in vivo activity of TTS-12 in a vaginal infection model with fluconazole-resistant C. albicans was studied in particular. Our studies revealed TTS-12 also showed in vivo activities against fluconazole-resistant yeasts. In conclusion, steroid saponins TTS-12 and TTS-15 from Tribulus terrestris L. have significant in vitro antifungal activity against fluconazole-resistant fungi, especially TTS-12 also showed in vivo activity against fluconazole-resistant C. albicans.

Animals↗
PubMed2005

Involvement of peroxiredoxin I in protecting cells from radiation-induced death.

Peroxiredoxin I (Prx-I), a key member of the peroxiredoxin family, reduces peroxides and equivalents through the thioredoxin system. Our previous work has shown that expression of Prx-I in mammalian cells increases following ionizing radiation (IR), indicating that Prx-I actively responds to IR-induced reactive oxygen species (ROS) and suggesting that Prx-I plays an important role in protecting cells from IR-induced death. To test this hypothesis, we suppressed the expression of Prx-I in SW480 cells by RNA interference. Our results show that IR induces the expression of Prx-I in SW480 cells in a dose- and time-dependent manner. The recombinant siRNA vector targeting Prx-I dramatically reduced the expression of Prx-I in SW480 cells. When Prx-I was knocked down in SW480 cells, the cells exhibited a decreased growth rate, a reduced antioxidant capability following IR and became more sensitive to IR-induced apoptosis. Together, our results demonstrate that Prx-I plays an important role in protecting cells from IR-induced cell death, which might be through scavenging IR-induced ROS in the cells.

Apoptosis↗
PubMed2005

The transfection of embryonic stem cells with Tet-on system and its responsiveness to doxycycline.

We transiently transfected pTet-on and pTRE2hyg-luciferase into the mouse embryonic stem cells (ESCs) using lipofectamine, and analyzed its inductive effect by adding serial concentrations of doxycycline (DOX). The results showed that in the transfected group, the luciferase activity of the cells was gradually increased along with the increasing concentration of DOX. While in the non-transfected group, the luciferase activity was not detectable even with DOX treatment. This indicated that the ESCs transfected with Tet-on system could response to DOX very well, and the regulation of target gene expression is dose dependent.

Animals↗
PubMed2005

Effects of pramlintide on postprandial glucose excursions and measures of oxidative stress in patients with type 1 diabetes.

OBJECTIVE: Oxidative stress has been shown to be increased in the postprandial period in patients with diabetes and has been implicated in the pathogenesis of micro- and macrovascular complications. The aim of this post hoc analysis was to assess the effects of pramlintide, an amylin analog shown to reduce postprandial glucose excursions in patients with diabetes, on markers of oxidative stress in the postprandial period. RESEARCH DESIGN AND METHODS: In a randomized, single-blind, placebo-controlled, crossover study, 18 evaluable subjects with type 1 diabetes underwent two standardized breakfast meal tests and received pramlintide or placebo in addition to their preprandial insulin. The plasma concentrations of glucose and markers of oxidative stress (nitrotyrosine, oxidized LDL [ox-LDL], and total radical-trapping antioxidant parameter [TRAP]) were measured at baseline and during the 4-h postprandial period. RESULTS: Compared with placebo, pramlintide treatment significantly reduced postprandial excursions of glucose, nitrotyrosine, and ox-LDL and prevented a decline in TRAP (P < 0.03 for all comparisons). Correlation analyses adjusted for treatment revealed a significant association between postprandial mean incremental area under the curve from 0 to 4 h (AUC(0-4 h)) for glucose and postprandial mean incremental AUC(0-4 h) for each measure of oxidative stress (r = 0.75, 0.54, and -0.63 for nitrotyrosine, ox-LDL, and TRAP, respectively; P < 0.001 for all correlations). CONCLUSIONS: These findings indicate that the postprandial glucose-lowering effect of pramlintide in type 1 diabetes is associated with a significant reduction in postprandial oxidative stress.

Adult↗
PubMed2005

[A rapid and high throughput method for apoE genotyping].

OBJECTIVE: To develop a new method that can determine the apolipoprotein E(apoE) genotypes rapidly in high throughput. METHODS: Genome DNA samples were extracted from the anticoagulated peripheral blood samples of 79 patients with Alzheimer's disease(AD) and 63 healthy individuals, and the 492 bp apoE gene fragments including 112 and 158 codons were amplified by polymerase chain reaction (PCR). With one PCR product, three recombined alleles (epsilon 2, epsilon 3 and epsilon 4) of apoE gene as controls were obtained by cloning and site-directed mutagenesis. The excess primers and dNTPs in all PCR products were removed by treatment with clean up reagents, then template-directed dye-terminator incorporation reaction (TDI) was performed and R110 or TAMRA labeled Acyclo-terminators were added into the mutation sites specifically. Fluorescence polarization value (FP) was measured using victor 2 multilabel counter and the polymorphisms in 112 and 158 condons of apoE gene were investigated. RESULTS: The apoE genotypes in recombined plasmid controls and all serum samples were analyzed using the authors' TDI-FP method, and the reliability and specificity were confirmed by DNA sequencing. The frequency of epsilon 4 allele in patients was significantly higher than that in controls, suggesting that apoE epsilon 4 allele gene is a risk factor for late-onset AD. CONCLUSION: TDI-FP is an easy, reliable and high throughput technology in analyzing polymorphism of apoE gene; it can be used in the prediction of susceptibility to AD in elderly individuals. Furthermore, it is an ideal method for large-scale screening and for studying the relationship between the allelic and genotypic frequencies of apoE and other diseases.

Aged↗
PubMed2005

[Molecular mechanisms of the protection of SNMC in HepG2 cell apoptosis].

OBJECTIVE: Apoptosis of the cells of liver cancer cell line HepG2 could be induced by TNF alpha and actinomycin D (Act D). In the current study, the molecular mechanism of the apoptosis protection of stronger neo-minophagen C (SNMC) to HepG2 cells was investigated. METHODS: SNMC was added to the HepG2 cell culture medium when the cell concentration reached 0, 2, 20, 100, 200, 800 microg/ml 30 min before their apoptosis were inducted with TNF alpha and Act D. A flow cytometry assay was performed to detect the cell apoptosis rate; electromicroscopy was employed to visualize the subcellular structure after apoptosis. DNA ladder formation was checked with genomic DNA agarose electrophoresis. The expression pattern of apoptosis related protein Caspase-3, Bcl-2 and Bax was detected by Western blot. RESULTS: After pretreatment with various concentrations of SNMC and 12 hours after treatment with TNF alpha and Act D, the HepG2 cell apoptosis rate and DNA ladder formation decreased dramatically when the SNMC concentration was higher in the media; the intracellular inactive form of Caspase-3 increased while the 17*10(3) active Caspase-3 decreased gradually. In addition, the expression of Bcl-2 increased and the expression of Bax decreased. Under the electromicroscope, the typical nucleolus condensation of HepG2 induced by TNF alpha and Act D was not seen among the 100 microg/ml SNMC treated cells. CONCLUSION: SNMC inhibits TNF alpha and Act D induced HepG2 cell apoptosis. This protective action may be regulated by intracellular apoptosis related factors.

Apoptosis↗
PubMed2005

[Methylation of hMLH1 gene promoter in gastric carcinoma with microsatellite instability].

BACKGROUND & OBJECTIVE: Mismatch repair (MMR) deficiency, characterized by microsatellite instability (MSI), is a major cause of hereditary nonpolyposis colorectal carcinoma (HNPCC). Our previous study showed that loss of MMR protein expression can also be seen in gastric carcinoma, but MMR gene mutation seldom occur. Promoter methylation, a main cause of suppressor gene inactivation, might also lead to defect of MMR gene function. This study was designed to investigate the relationship of hMLH1 gene promoter methylation status to MSI in gastric carcinoma, and analyze its action as a risk factor of carcinogenesis. METHODS: DNA was extracted from 52 samples of gastric carcinoma and their adjacent non-cancerous gastric mucosa. Polymerase chain reaction (PCR) was used to amplify microsatellite loci BAT-26, D17S261, D3S1283, D2S123, and D3S1611. MSI was studied by capillary electrophoresis. Methylation of hMLH1 gene promoter was detected by restrictive endonuclease digestion, expression of hMLH1 protein was detected by immunohistochemistry. RESULTS: Of the 52 specimens of gastric carcinoma, 13 with high MSI (MSI-H), 2 with low MSI (MSI-l), and 37 with microsatellite stability (MSS). Frequency of hMLH1 promoter methylation was significantly higher in the 13 specimens of gastric carcinoma with MSI-H than in the 39 specimens of gastric carcinoma with MSI-L or MSS (100% vs. 2.6%, P<0.01). Furthermore, frequency of hMLH1 promoter methylation was significantly higher in the 13 specimens of adjacent non-cancerous gastric mucosa of gastric carcinoma with MSI-H than in the 39 specimens of adjacent non-cancerous gastric mucosa of gastric carcinoma with MSI-L or MSS (46.2% vs. 2.6%, P<0.01). The methylation status was accordant with loss of hMLH1 protein expression. Methylation of hMLH1 gene promoter had no relation with differentiation and clinical stage of gastric carcinoma. CONCLUSION: Methylation of hMLH1 gene promoter exists in gastric carcinoma tissues with MSI-H, and their adjacent non-cancerous gastric mucosa, it may be a risk factor of carcinogenesis of gastric carcinoma.

Adaptor Proteins, Signal Transducing↗
PubMed2005

[Screening of human scFv against IL-8 from phage antibody library].

AIM: To screen human scFv against IL-8 from phage antibody library. METHODS: IL-8-His fusion protein was expressed in E.coli BL21 (DE3) transfected with prokaryotic expression vector pRSET-IL-8 and was purified by affinity chromatography. Specific antibody was screened by 3 rounds of panning of phage antibody library with the fusion protein. The antigen binding activity and DNA sequences of positive clones were determined and analyzed. RESULTS: After 3 rounds of panning, 2 positive clones were obtained which could bind IL-8 specifically. DNA sequence analysis showed both of the 2 VH genes belonged to human IgG VH3 subgroup, and the Vlambda gene belonged to human VlambdaDPL5 and VlambdaDPL2 subgroups,respectively. CONCLUSION: It is feasible to obtain human anti-IL-8 antibody by phage display technique, which provides the basis for further research on psoriasis and other related diseases.

Antibodies↗
PubMed2005

[Observing the distribution of Annexin I and cPLA2 in the palatal process of mice by immunohistochemical staining].

OBJECTIVE: To observe the distribution of Annexin I and cytosolic phospholipose A2 (cPLA2) in the palatal process of dexamethasome teratogenerated mice. METHODS: Cutting along the coronary plane of the heads of fetal mice to obtain palate in the 14th, 15th, 16th day of gestation by 10-week-old in-bred mice. The distribution of Annexin I and cPLA2 was checked by immunohistochemical staining. RESULTS: During the fusing of the palatal processes, the staining of Annexin I and cPLA2 was positive in the epithelial and mesenchymal cells of the palatal process, and the intensity of staining changed with time. CONCLUSION: Annexin I and cPLA2 can modulate the development of fetal palate to some extent, and they may be important mediators in the development of cleft palate induced by dexamethasone.

Animals↗
PubMed2005

[Polysomnography analysis in children].

OBJECTIVE: To analyze the characteristics of Polysomnography (PSG) in children with obstructive sleep apnea-hypopnea syndrome(OSAHS). METHOD: Forty-five children with sleep breathing disorder were studied with 32 guide PSG and analyzed by Polysmith. PSG results of OSAHS children were compared with primary snore group. RESULT: The mean age of OSAHS children was(7.3 +/- 3.8) years and the mean body weight was (40.1 +/- 19.7) kg. The mean value of NREM stage 1, stage 2, stage 3+4 and REM stage was(21.4 +/- 13.2)%, (43.1 +/- 13.7)%, (26.1 +/- 14.0) % and (9.4 +/- 6.0) % respectively. The sleep structure between OSAHS group and primary snore group was not significant (P > 0.05). The mean value of AHI of OSAHS children was(12.8 +/- 8.1) h. AI was (6.7 +/-6.6)h, HI was(6.1 +/- 5.1)h. CONCLUSION: The sleep structure of children is prefect and mild effected by OSAHS.

Adolescent↗
PubMed2005

[Structural characteristics and heterogeneity analysis of yard-greenbelts in Shenyang city].

The analysis of the landscape and pattern of yard-greenbelts in Shenyang city indicated that residential greenbelt had the highest green path number, occupying 32.2% of all greenbelt types, but the virescence situation in residential area was the worst because its greenbelt ratio was only 19.5% in average. The average area of all yards was 4.04 hm2, with an average greenbelt of 0.93 hm2, and the green belt ratio was 23% in average that was lower than the standard established by the government. About 62.7% of all yards were lower than 15% in virescence, and 30% of them had a < 13.3% of virescence. Micro-green patch was dominant (over 70%) in Shenyang yard-greenbelts. Landscape diversity index of residential areas was the highest, while that of hospital and army units was the lowest. The dominant degrees of all yard-greenbelt types in the researched 7 districts of the city were obviously different. The dominance of factory greenbelt in Yuhong district was 31.23 times of that in Heping district. The evenness indexes were also very different, the highest in residential greenbelt and the lowest in army unit. The highest fragmentation degree was in residential greenbelt and the lowest in army unit. The fragmentation degrees of old districts, especially in Shenhe district were more serious than the new districts.

City Planning↗
PubMed2005

[Content and distribution of fluorine in Chinese coals].

Nationwide sampling program is designed according to the resources distribution and coal-forming periods as well as coal rank and yield of coal in China, and 305 coal samples were collected from 26 provinces, municipalities and autonomous regions. Fluorine in coal is determined by pyrohydrolysis / fluoride-ion selective electrode method. Fluorine in coals is mainly of an inorganic nature. Coal rank has no effect on fluorine content. The influence of a factor, such as geological age, on fluorine contents might be concealed by other factors, more research should be done to discern it. The distribution of fluorine in each province, municipality and autonomous region's coals is studied, and the fluorine source in coal-burning endemic fluorosis areas should be estimated over again. The contents of fluorine in Chinese coals show logarithm normal distribution, and 90% of values ranged from 47mg/kg to 347mg/kg, the average fluorine content in Chinese coals was designated as the geometric mean, 136mg/kg. Fluorine in Chinese coals is within the world coal's range.

Air Pollutants↗
PubMed2005

[Detection of antibody against Helicobacter pylori UreB by fluorescence polarized immunoassay using single epitope synthetic peptide as antigen].

AIM: To develop a new method for antibody detection based on fluorescence polarization (FP) technique. METHODS: BALB/c mice were immunized with single epitope synthetic 8 branches peptide antigen (SVEVGKVADL)8 of Helicobacter pylori (Hp) UreB protein. FP values of the corresponding linear peptide antigen labeled with FITC in different concentration were measured to determine the optimal concentration of the antigen. The antigenicity of the synthetic linear peptide was identified by FP assay. Then, the antibody-positive and negative murine sera were used in FP assay to determine the optimal dilution factor of serum samples. To apply FP technique in Hp antibody detection, 126 human serum samples were detected either by FPIA (fluorescence polarized immunoassay) using the single epitope linear synthetic peptide as antigen or by a commercial ELISA kit. Then, receiver operating characteristic (ROC) curve analysis was performed on the FPIA results by MedCalc software. RESULTS: The UreB single epitope peptide had strong antigenicity. 1.0 nmol/L of the synthetic linear peptide labeled with FITC was the optimal concentration of the antigen and the optimal dilution factor of serum sample was 1:25. In 77 Hp antibody-positive serum samples detected by ELISA, 66 samples were positive by FP detection method. The sensitivity and specificity of the FPIA assay was 85.7% and 98%, respectively. CONCLUSION: The single epitope synthetic peptide antigen can be used in FP method for rapid detection of serum antibody against Hp UreB. The established FP assay for antibody detection may be used in clinical diagnosis in the future.

Animals↗