Biomedical subjects

Xia Wang

Publications and source records attributed to Xia Wang.

At least 37 records · Page 2Linked to original sources

PubMed2006

Recombinant production of fibrinogenase IV from Agkistrodon acutus venom and its preliminary evaluation.

A novel metalloproteinase, recombinant fibrinogenase IV (rFIVa), was expressed and purified from Agkistrodon acutus venom. It is a single-chain protein with an apparent molecular weight of 27 kDa. Western blot showed that it had a good immunological reaction against anti-FIVa rabbit serum. The kinetic parameters Km and Kcat of rFIVa on the substrate T6140 were 7.471 x 10(-4) mol/l and 5.103 x 10(-5) s(-1). RFIVa cleaved preferentially the alpha-chain, and the beta- and gamma-chains of fibrinogen were also cleaved when the incubation time was prolonged. The administration of rFIVa (1.8 and 5.4 mg/kg) to animals with acute blood-stasis model produced a decrease in fibrinogen to control values. To our knowledge, this is the first report of the expression, purification, and evaluation of recombinant fibrinogenase IV, which belongs to class P-I metalloproteinase from A. acutus venom.

Agkistrodon↗

PubMed2006

17-allylamino-17-demethoxygeldanamycin synergistically potentiates tumor necrosis factor-induced lung cancer cell death by blocking the nuclear factor-kappaB pathway.

Nuclear factor-kappaB (NF-kappaB), a survival signal induced by tumor necrosis factor (TNF), contributes substantially to the resistance to TNF-induced cell death. Previous studies suggest that heat shock protein 90 (Hsp90) regulates the stability and function of receptor-interaction proteins (RIP) and IkappaB kinase beta (IKKbeta), the key components of the TNF-induced NF-kappaB activation pathway. In this study, we showed that the Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17AAG) was synergistic with TNF to induce apoptotic cell death in a panel of lung tumor-derived cell lines. Treatment with 17AAG caused degradation of RIP and IKKbeta that, in turn, blocked TNF-induced NF-kappaB activation and antiapoptotic gene expression. The synergistic cytotoxicity was detected only when TNF treatment followed 17AAG preexposure. Importantly, the potentiation of cell death was abolished in NF-kappaB-disabled cells that express a nondegradable IkappaBalpha mutant (IkappaBalphaAA). These results suggest that the cytotoxicity seen with 17AAG and TNF treatment results from blocking TNF-induced NF-kappaB activation. The other components of the TNF receptor I signaling cascade were not altered, whereas TNF-induced c-Jun NH(2)-terminal kinase activation and apoptosis were potentiated. A similar synergism for inducing apoptosis was also observed in 17AAG-treated and TNF-related apoptosis-inducing ligand (TRAIL)-treated cancer cells. Our results suggest that NF-kappaB plays a key role in the resistance of lung cancer cells to TNF and TRAIL and that disabling this survival signal with 17AAG followed by TNF or TRAIL treatment could be an effective new therapeutic strategy for lung cancer.

Apoptosis↗

PubMed2006

A general strategy for creating "inactive-conformation" abl inhibitors.

Kinase inhibitors that bind to the ATP cleft can be broadly classified into two groups: those that bind exclusively to the ATP site with the kinase assuming a conformation otherwise conducive to phosphotransfer (type I), and those that exploit a hydrophobic site immediately adjacent to the ATP pocket made accessible by a conformational rearrangement of the activation loop (type II). To date, all type II inhibitors were discovered by using structure-activity-guided optimization strategies. Here, we describe a general pharmacophore model of type II inhibition that enables a rational "hybrid-design" approach whereby a 3-trifluoromethylbenzamide functionality is appended to four distinct type I scaffolds in order to convert them into their corresponding type II counterparts. We demonstrate that the designed compounds function as type II inhibitors by using biochemical and cellular kinase assays and by cocrystallography with Abl.

Adenosine Triphosphate↗

PubMed2006

NANOGP8 is a retrogene expressed in cancers.

Nanog is a transcription factor that plays key roles in the self-renewal and maintenance of pluripotency in human embryonic stem (ES) cells. Among Nanog's 11 pseudogenes, NANOGP8 theoretically could be a retrogene, but was considered unlikely as it has not been identified in any expressed sequence tags (ESTs). In this study, we found that NANOGP8 was expressed in several cancer cell lines and in all cancer tissues tested. The complete coding sequence was cloned and the sequence is highly homologous to that of Nanog. We were also able to detect its protein expression using anti-Nanog antibody in recombinant Escherichia coli and some cancer cell lines tested. In addition, expression of NANOGP8 in NIH3T3 cells can promote cell proliferation. The expression of NANOGP8 in cancer cell lines and cancer tissues suggests that NANOGP8 may play important roles in tumorigenesis. This work not only has potential significance in stem cell and cancer research, but it also raises the possibility that some of the human pseudogenes may have regulatory functions.

Animals↗

PubMed2006

Modeling for gellan gum production by Sphingomonas paucimobilis ATCC 31461 in a simplified medium.

Gellan gum production was carried out by Sphingomonas paucimobilis ATCC 31461 in a simplified medium with a short incubation time, and a kinetic model for understanding, controlling, and optimizing the fermentation process was proposed. The results revealed that glucose was the best carbon source and that the optimal concentration was 30 g liter(-1). As for the fermenting parameters, considerably large amounts of gellan gum were yielded by an 8-h-old culture and a 4% inoculum at 200 rpm on a rotary shaker. Under the optimized conditions, the maximum level of gellan gum (14.75 g liter(-1)) and the highest conversion efficiency (49.17%) were obtained in a 30-liter fermentor in batch fermentation. Logistic and Luedeking-Piret models were confirmed to provide a good description of gellan gum fermentation, which gave some support for the study of gellan gum fermentation kinetics. Additionally, this study is the first demonstration that gellan gum production is largely growth associated by analysis of kinetics in its batch fermentation process. Based on model prediction, higher gellan gum production (17.71 g liter(-1)) and higher conversion efficiency (57.12%) were obtained in fed-batch fermentation at the same total glucose concentration (30 g liter(-1)).

Biotechnology↗

PubMed2006

[Research advances on the relationship of PI3-kinase/Akt/mTOR pathway and epigenetic modification].

The mammalian target of rapamycin (mTOR) has been shown to link growth factor signaling and posttranscriptional control of protein translation through activation of the PI3K/Akt pathway, which is frequently involved in cell cycle progression. The inhibition of mTOR has promising potential in anticancer and immunosuppressive therapies, and additional phase II clinical trials are ongoing. Epigenetic modification, which involves DNA methylation, histone modification and chromatin remodeling, as well as the recently described RNAi mechanism, can initiate the formation of silenced chromatin. Persistent activation or inhibition of the mTOR pathway may affect epigenetic modification. In this paper, we reviewed the research advances in the relationship between PI3K/Akt/mTOR and epigenetic modification.

Animals↗

PubMed2006

[Effect of hyperbaric oxygenation on neural stem cells and myelin in neonatal rats with hypoxic-ischemic brain damage].

OBJECTIVE: This study investigated the effect of hyperbaric oxygenation (HBO) on neural stem cells (NSCs) and myelin in neonatal rats following hypoxic-ischemic brain damage (HIBD) and aimed to explore the possible mechanism of the protective effect of HBO on HIBD. METHODS: Seven-day-old Sprague-Dawley rat pups were randomly assigned into 4 groups: Normal control, HIBD, hyperbaric air (HBA), and HBO groups (n=30 each). The HIBD model was produced by permanent occlusion of the left common carotid artery and 2 hrs hypoxemia exposure (8% O2 at 37 degrees C). HBA and HBO treatment was administered (2 ATA, once daily for 7 days) in the HBA and HBO groups respectively 1 hr after HIBD. BrdU immunohistochemistry was used to detect the NSCs in the sub-ventricle zone (SVZ) of the lateral ventricle and the dentate gyrus (DG) of the hippocampus. The myelin damage was assessed by myelin basic protein (MBP) immunostaining. RESULTS: The BrdU-positive cells in the SVZ and the DG of the ischemic hemisphere in the HIBD group were dramatically decreased compared with those of the Normal control group at 3 weeks post-HIBD (P < 0.01). The HBO treatment resulted in an increase of BrdU-positive cells in the DG from 153.7 +/- 37.0 to 193.7 +/- 38.8 (P < 0.05). The nestin expression in the HIBD and HBA groups was reduced compared with that in the Normal control group. There was no difference in the nestin expression between the HBO and the Normal control groups. Hypoxia-ischemia (HI) led to marked myelin damage at 1 week post-HIBD. HBO or HBA treatment alleviated the damage. CONCLUSIONS: The HBO treatment can result in the proliferation of BrdU-positive cells and alleviate the myelin damage following HIBD in neonatal rats, thereby offering neuroprotectivity against HI insults.

Animals↗

PubMed2006

[Study of induction of tumor specific cytotoxic T lymphocyte by using tumor-derived exosome].

OBJECTIVE: To investigate whether the exosomes derived from Tca8113 could induce production of tumor-specific T cells when pulsed onto dendritic cells. METHODS: Tca8113 cell was cultured with RPIM1640, isolated and purified the tumor-derived exosomes from the culture supernatants by ultrafiltration with Millipore centrifual filter devices; frozen and thawed Tca8113 cells to get frozen tumor antigens (FTA). The exosomes and FTA was pulsed onto DC generated from normal human peripheral blood mononuclear cell (PBMC) in vitro. The DC pulsed with FAP or exosomes cocultured with the peripheral blood lymphocytes to transform T cell into specific CTL. To observe the killing and wounding activity of CTL, the CTL and Tca8113 cells were mixed at a ratio of 20 to 1, SPCA-1 cells and 95-D cells was evaluated as control group. RESULTS: The CTL induced by DC pulsed with FAP or exosomes had significant activity killing Tca8113 (P < 0.01); Moreover the CTL induced by DC pulsed with exosomes could also kill SPCA-1 cells (P < 0.05), but the CTL induced by DC pulsed with FTA had not this function. CONCLUSION: Exosomes derived from tumour accumulate in culture supernatants. Exosomes are a natural and new source of tumour-rejection antigens, opening up new avenues for immunotherapy against oral cancers. The exosome-specific CTL could kill another kind of tumor, so tumor-derived exosomes may contain shared tumor-rejection antigens.

Antigens, Neoplasm↗

PubMed2006

[Estrogenic and androgenic effects of low dose raw water organics].

OBJECTIVE: To study the estrogenic and (anti)androgenic effects caused by low-dose raw water organic compounds. METHODS: The organic compounds from raw water was concentrated with solid-phase extraction. Rodent 3-day Uterotrophic Assay and Hershberger assay, the assays recommended in EPA Tier 1 Screening Program for EDCs, were employed to investigate estrogenic and (anti) androgenic effects of these chemical mixture exposure. Doses equivalent to human daily intake were administered to laboratory animals. RESULTS: Low-dose effects of water organic compounds,which refer to levels of human daily water intake, did not show a statistical difference of weights of mouse uterus and rat sexual accessory glands(SAG) from the negative control in Uterotrophic Assay and Hershberger Assay, except the height of uterus epithelial in 4.0 L / 60 kg was significant difference with negative control. CONCLUSION: Based upon the water sample tested, it did not suggest that the low-dose raw water organic compounds exposure equivalent to people daily drinking water intake cause rodents (anti)androgenic in vivo effects, but it demonstrated a suspected estrogenic effect.

Androgens↗

PubMed2006

[Protective effects of baicalin pretreatment on hypoxic-ischemic brain damage in neonatal rats].

OBJECTIVE: Previous research suggests that dexamethasone (Dex) pretreatment protects neonatal rats against hypoxic-ischemic brain damage (HIBD). Some of the pharmacological effects of baicalin (a traditional Chinese medicine extracted from Scutellaria baicalensis Georgi) are similar to Dex. This study was designed to explore the effect of baicalin on the neuronal apoptosis following HIBD in neonatal rats. METHODS: Six-day-old Sprague-Dawley rats were randomly assigned into Control (without HI), HIBD, Dex-pretreatment and post-treatment, Baicalin-pretreatment and -post-treatment groups. HIBD was induced by ligating the left common carotid artery, followed by exposure to hypoxia. In the pretreatment groups either baicalin (16 mg/kg) or Dex (0.1 mg/kg) was administered to the rats 24 hrs before HIBD; in the post-treatment groups baicalin or Dex was given 30 minutes after HIBD. The rat pups were sacrificed on postnatal day 10, and brain tissues were harvested. Brain water content was determined, morphological changes were observed under a light microscope, and neuronal apoptosis was measured by terminal deoxynucleotidyl transferase mediated dUTP biotin nick end labeling (TUNEL) staining. RESULTS: The brain water content and the number of apoptotic cells were significantly higher in the HIBD group than those of the Control group (P < 0.05). Both baicalin and Dex pretreatment decreased the brain water content from 88.9 +/- 1.7 % (HIBD group) to 87.4 +/- 0.7% (baicalin) or 87.3 +/- 0.6% (Dex) (P < 0.05) and the number of apoptotic cells were reduced from 251 +/- 28 (HIBD group) to 102 +/- 47 (baicalin) or 75 +/- 26 (Dex) (P < 0.05). Baicalin and Dex post-treatment had no effects on the brain water content and the number of apoptotic cells. Loss and degeneration of neurons could be observed in the HIBD group. Baicalin and Dex pretreatment significantly alleviated neuronal injury, but post-treatment did not. CONCLUSIONS: Pretreatment with baicalin, as with Dex, has a protective effect against HIBD in neonatal rats, but baicalin or Dex post-treatment do not reverse the neuronal injuries.

Animals↗

PubMed2006

[Analysis of fatty acids in Gmnocypris przewalskii oil by gas chromatography/mass spectrometry with base-catalyzed transesterification].

The composition of fatty acids (FA) in Gymnocypris przewalskii oil was identified and quantified by gas chromatography (GC)/electron impact (EI) mass spectrometry (MS). A base-catalyzed transesterification method was used to convert fatty acids to methyl esters. The lipids were extracted using petroleum ether and the total lipids in dried meat and skin of Gymnocypris przewalskii were about 25%. Forty-seven fatty acids were identified in the current study. Main types of fatty acids found in the oils were normal saturated, mono-branched, multi-branched, cyclopropane, furanoid, normal monounsaturated and polyunsaturated fatty acids. Saturated fatty acids were approximately 25. 7% of the total, and the main components were C(14:0) (3.4%), C(16:0) (19.4%) and C(18:0) (1.1%). Unsaturated fatty acids were totally 73.6%, and the major components of monounsaturated fatty acids were C(16:1 (9)) (19.8%), C(18:1) (9)) (18. 6%) and C(18:1 (11)) (7.3%); polyunsaturated fatty acids were mainly composed of C(18:2 (9,12)) (4.8%), C(18:3 (9, 12, 15)) (3.1%), C(20:4 (5, 8, 1, 14)) (1.2%), C(20:5 (5, 8, 11, 14, 17)) (EPA, 9.4%) and C(22:6 (4, 7, 10, 13, 16, 19)) (DHA, 6.7%). Especially, furyl-, cyclopropane- and several odd and branched chain fatty acids were found in Gymnocypris przewalskii oil. It is thus an important dietary resource of functional fatty acids.

Animals↗

PubMed2006

[Study on bisphenol A induced primary cultured mesencephalic neuronal cell injury by oxidative stress].

OBJECTIVE: To investigate the effect and mechanism of bisphenol A, a common EDCs, on the primary cultured mesencephalic neuronal cell injury. METHODS: mesencephalic neuronal cells were obtained from embryonic 14-15 day SD fetuses and were cultured in serum free medium for 4 or 7 days in vitro, 1,10,25,50 and 100 micromol/L bisphenol A were added to the medium and intracellular ROS, SOD, MDA, GSH were measured after 24 or 48hours, respectively. Flow cytometry was used to detect the neuronal cell apoptosis. Tyrosine hydroxylase immunohistochemistry was used to identity and count the ratio of dopaminergic neuronal cell. RESULTS: The intracellular ROS was dose dependently increased by bisphenol A in all treated groups, and it appeared to be a nonselective effect when the concentration of bisphenol A were higher than 50 micromol/L, and concomitantly decreased SOD, GSH and increased MDA. The apoptotic neuronal cells were significantly increased at 501 micromol/L and 100 micromol/L. The ratio of Tyrosine hydroxylase positive neuronal cell was dose dependently decreased with the concentration of bisphenol A. CONCLUSION: ROS induced by bisphenol A may play a major role in its cytotoxicity on dopaminergic neuronal cell.

Animals↗

PubMed2006

[Alcohol inhibited the expression of glial fibral acidic protein and S100 of astrocytes].

OBJECTIVE: To explore effects of alcohol on the expression of gial fibral acidic protein (GFAP) and S100 of astrocytes in brain. METHODS: Different dosages of alcohol (2,5 and 20 mmol/L) were administered to astrocytes of fetal rat brain in vitro. The expression of GFAP and S100 of astrocytes was detected by immunocytochemistry, respectively. RESULTS: With the dosage of alcohol increasing, the expression of GFAP and S100 was reduced and the number of astrocytes in high dosage group was observed to be decreased slightly. CONCLUSION: It suggested that alcohol could repress the expression of GFAP and S100 of astrocytes, which might be the main mechanism of developmental abnormalities of central nervous system induced by alcohol.

Animals↗

PubMed2006

[Factors influencing successful isolation of mesenchymal stem cells from human umbilical cord blood].

OBJECTIVE: Emerging evidences suggest that mesenchymal stem cells (MSCs) can be isolated from human umbilical cord blood (HUCB) and cultured in vitro, the same as the MSCs derived from bone marrow. However previous attempts to isolate MSCs from UCB showed a low rate of success (less than 30%). The present study was conducted to clarify the factors that influence the yields of MSCs from HUCB of different gestational age deliveries and to observe the bioactivity of MSCs derived from UCB. METHODS: HUCB units were divided into three groups: gestational age (GA) 40 w group (n = 11); GA 36 w group (n = 6); GA 32 w or less than 32 w group (n = 5), cultured with optimal culture conditions. The relationship of the yields of MSCs derived from HUCB with several factors such as GA, the collected volume of HUCB and the mononuclear cells (MNCs) count of UCB, and the relationship among these factors were investigated. The bioactivity was observed by drawing the growth curve, calculating the population doubling, counting the fibroblast colony forming units (CFU-F) and detecting the surface antigen expression of MSCs by flow cytometry. RESULTS: The success rate of generating MSCs cells was up to 54.5%. There were some correlations between the success rate and such factors as the MNCs count, the GA and the volume of UCB. The rate could be enhanced to 83.3% when the MNCs count was more than 1.25 x 10(8)/L. There was a negative correlation between the MNCs count in the same HUCB volume and the gestational age. The count of CFU-F varied with gestational age, the count of CFU-F was higher in smaller gestational age than the older. In the primary culture some cells displayed a fibroblast-like morphology and expressed MSCs-related antigens CD29, CD105, and the expression rate of these antigens were enhanced from 62.1% to 85.0% in one passage. The hematopoietic cells antigens CD34 and CD45 were less than 3% all the time. CONCLUSIONS: The success rate could be increased when the MNCs count was more then 1.25 x 10(8)/L. There was a negative correlation between the MNCs count of the same UCB volume and the gestational age, the activity to form the CFU-F of UCB varied with gestational age; isolation of MSCs from UCB of pre-term deliveries may be relatively easier as compared to those from full term deliveries.

Cell Count↗

PubMed2006

[Study on remote sensing of methane leakage using a tunable diode laser].

The leak of natural gas is not only an economic loss, but also the fountain of danger. Conventional detection techniques of natural gas pipe leak have low efficiency and slow respond time, therefore, it is difficult for them to suit practice application. Optical sensors based on NIR tunable diode laser absorption spectroscopy were widely used because of high sensitivity, small volume and less maintenance. In the present paper, a portable remote sensor of natural gas pipeline leak was reported. The sensor used a ratio of second to first harmonic signals as calibration method, and the results show a good consistency between the concentrations and the ratios of second to first harmonic signals. The effect of different topographic scattering targets on the ratio detection was measured and analyzed. The results show that the ratio of second to first harmonic signals can be used in practical application.

English Abstract↗

PubMed2006

[Combined assay of serum prostate specific antigen and chromogranin A helps diagnosis of prostate cancer].

OBJECTIVE: To evaluate the significance of the combined assay of chromogranin A (CgA) and prostate specific antigen (PSA) in the diagnosis of prostate cancer. METHODS: Serum CgA and PSA were detected by ELISA technique in 55 cases of prostate cancer (PCa), 25 cases of benign prostate hyperplasia (BPH), and 50 cases of normal subjects (control). RESULTS: The serum CgA level in the PCa group was significantly higher than those in the control and BPH groups (P < 0.05), and increased with clinical stages. The parallel and serial tests associated with serum PSA and CgA raised the rate of detection of prostate cancer. CONCLUSION: The combined assay of serum PSA and CgA is of significant clinical value in raising the rate of diagnosis of prostate cancer, as well as in staging and prognosing the disease.

Aged↗

PubMed2005

Role of cysteine residues in the function of human UDP glucuronosyltransferase isoform 1A1 (UGT1A1).

Bilirubin glucuronidation, catalysed by UGT1A1 [UGT (UDP glucuronosyltransferase) isoform 1A1, EC 2.4.1.17], is critical for biliary elimination of bilirubin. UGT1A1 deficiency causes CN-1 (Crigler-Najjar syndrome type 1), which is characterized by potentially lethal unconjugated hyperbilirubinaemia. Nucleotide sequence analysis of UGT1A1 in two CN-1 patients revealed that patient A was homozygous for a nt 530 G-->A (where nt 530 G-->A means guanine to adenine transition at nucleotide 530) mutation, predicting a C177Y substitution, and patient B had a nt 466 T-->C mutation on one allele and a nt 1070 A-->G mutation on the other, predicting a C156R and a Q357R substitution respectively. All 11 cysteine residues of mature human UGT1A1 are highly conserved in other human UGT isoforms and in rat, mouse and Rhesus monkey UGT1A1, suggesting their functional importance. Expression of mutagenized UGT1A1 plasmids showed that substitution of any of the seven cysteine residues located within the endoplasmic reticulum cisternae (including those mutated in patients A and B) abolished UGT1A1 activity or markedly increased its apparent K(m) for bilirubin. Substitution of the three cysteine residues within the C-terminal cytosolic tail had minimal effect on basal UGT1A1 activity, but prevented UGT1A1 activation by UDP-GlcNAc. N-Ethylmaleimide did not inhibit UGT1A1 activity in native microsomes, but prevented UGT1A1 activation by UDP-GlcNAc and inhibited the activity in digitonin-permeabilized microsomes. Dithiothreitol did not affect UGT1A1 activity in human liver microsomes. Together, the results suggested that free thiol groups, but not disulphide bonding, of seven cysteine residues within the intracisternal region of human UGT1A1 are important for its catalytic activity, while cysteine residues in the cytosolic domain may be involved in its physiological activation by UDP-GlcNAc.

Amino Acid Sequence↗

PubMed2005

Expression of Nanog gene promotes NIH3T3 cell proliferation.

Cells are the functional elements in tissue engineering and regenerative medicine. A large number of cells are usually needed for these purposes. However, there are numbers of limitations for in vitro cell proliferation. Nanog is an important self-renewal determinant in embryonic stem cells. However, it remains unknown whether Nanog will influence the cell cycle and cell proliferation of mature cells. In this study, we expressed Nanog in NIH3T3 cells and showed that expression of Nanog in NIH3T3 promoted cells to enter into S phase and enhanced cell proliferation. This suggests that Nanog gene might function in a similar fashion in mature cells as in ES cells. In addition, it may provide an approach for in vitro cell expansion.

Animals↗