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Biomedical subjects

Xiang Wang

Publications and source records attributed to Xiang Wang.

At least 37 records · Page 2Linked to original sources
PubMed2006

Endomorphin1 and endomorphin2, endogenous potent inhibitors of electrical field stimulation (EFS)-induced cholinergic contractions of rat isolated bronchus.

In the present study, we determined whether endomorphin1 (EM1) and endomorphin2 (EM2), selective endogenous mu-opioid receptor (MOR) agonists, inhibited the response to EFS in rat isolated bronchus in a concentration- and frequency-dependent manner. EM1 (1 microM) produced significant inhibition at relatively low frequencies (< 5 Hz) (74.02 +/- 5.53%, 56.16 +/- 10.24% and 37.64 +/- 5.92% inhibition at 1, 2 and 4 Hz, respectively, p < 0.05 versus control), but no significant inhibition at 8, 16, 32 and 64 Hz (17.15 +/- 9.4%, 14.51 +/- 4.23%, 9.11 +/- 2.38% and 5.93 +/- 3.5%, respectively, p > 0.05 versus control). Similar modulations were observed in response to EM2 (1 microM). It is therefore considered that the inhibition effects of EM1 and EM2 may take place at frequencies under physiological conditions. Furthermore, EM1 and EM2 (0.01-10 microM) induced inhibition of cholinergic constriction in a dose-dependent manner at 1, 2 and 4 Hz. The inhibitory effect on EFS was blocked by the opioid receptor antagonist naloxone (10 microM), indicating that opioid receptors were involved. Neither EM1 nor EM2 (1 microM) had an effect on the contractile response to exogenous acetylcholine, indicating a prejunctional effect. All the results indicate that EM1 and EM2 are potent inhibitors of EFS-induced cholinergic bronchoconstriction. These also imply that EM1 and EM2 may modulate cholinergic bronchoconstriction under physiological conditions and that these tetrapeptides could have therapeutic potential in the treatment of airway diseases.

Animals↗
PubMed2006

Mechanism of cytosol phospholipase C and sphingomyelinase-induced lysosome destabilization.

Lysosomal disintegration may cause apoptosis, necrosis and some diseases. However, mechanisms for these events are still unclear. In this study, we measured lysosomal beta-hexosaminidase free activity, membrane potential and intralysosomal pH. The results revealed that the cytosolic extracts of rat hepatocytes could increase the lysosomal permeability to both potassium ions and protons, and osmotically destabilize lysosomes via K(+)/H(+) exchange. The effects of cytosol on lysosomes could be completely abolished by D609, which inhibited both phospholipase C and sphingomyelinase, and partly prevented by sphingomyelinase inhibitor Ara-AMP, but not by the inhibitors of PLA(2). Moreover, purified phospholipase C could destabilize the lysosomes while phospholipase A(2) and phospholipase D did not produce such effects. The cytosolic phospholipases hydrolyzed lysosomal membrane phospholipids by 50%, which could be prevented by D609. Disintegration of the cytosol-treated lysosomes biphasically depended on the cytosolic [Ca(2+)]. The cytosol did not disintegrate lysosomes below 100 nM or above 10 muM cytosolic [Ca(2+)], but markedly destabilized lysosomes at about 340 nM [Ca(2+)]. The results suggest that cytosolic phospholipase C and sphingomyelinase may be responsible for the alterations in lysosomal stability by increasing the ion permeability.

Animals↗
PubMed2006

Magnetic iron oxide nanoparticles for biorecognition: evaluation of surface coverage and activity.

Modifying the surfaces of magnetic nanoparticles (MNPs) by the covalent attachment of biomolecules will enable their implementation as contrast agents for magnetic resonance imaging or as media for magnetically assisted bioseparations. In this paper we report both the surface coverage and the activity of IgG antibodies on MNPs. The antibodies were immobilized on gamma-Fe2O3 nanoparticles by conventional methods using aminopropyltriethoxy silane and subsequent activation by glutaraldehyde. Novel fluorescence methods were used to provide a quantitative evaluation of this well-known approach. Our results show that surface coverage can be stoichiometrically adjusted with saturated surface coverage occurring at approximately 36% of the theoretical limit. The saturated surface coverage corresponds to 34 antibody molecules bound to an average-sized MNP (32 nm diameter). We also show that the immobilized antibodies retain approximately 50% of their binding capacity at surface-saturated levels.

Antibodies↗
PubMed2006

Microdamage propagation in trabecular bone due to changes in loading mode.

Microdamage induced by falls or other abnormal loads that cause shear stress in trabecular bone could impair the mechanical properties of the proximal femur or spine. Existing microdamage may also increase the initiation and propagation of further microdamage during subsequent normal, on-axis, loading conditions, resulting in atraumatic or "spontaneous" fractures. Microdamage formation due to shear and compressive strains was studied in 14 on-axis cylindrical bovine tibial trabecular bone specimens. Microdamage was induced by a torsional overload followed by an on-axis compressive overload and quantified microscopically. Fluorescent agents were used to label microdamage and differentiate damage due to the two loading modes. Both the microcrack density and diffuse damage area caused by the torsional overload increased with increasing shear strain from the center to the edge of the specimen. However, the mean microcrack length was uniform across the specimen, suggesting that microcrack length is limited by microstructural features. The mean density of microcracks caused by compressive overloading was slightly higher near the center of the specimen, and the diffuse damage area was uniform across the specimen. Over 20% of the microcracks formed in the initial torsional overloading propagated during compression. Moreover the propagating microcracks were, on average, longer than microcracks formed by a single overload. As such, changes in loading mode can cause propagation of microcracks beyond the microstructural barriers that normally limit the length. Damage induced by in vivo off-axis loads such as falls may similarly propagate during subsequent normal loading, which could affect both remodeling activity and fracture susceptibility.

Animals↗
PubMed2006

Isolation and characterization of the human D-glyceric acidemia related glycerate kinase gene GLYCTK1 and its alternatively splicing variant GLYCTK2.

Deficiency of human glycerate kinase leads to D-glycerate acidemia/D-glyceric aciduria. Through PCR cloning assisted by in silico approach, we isolated the human glycerate kinase genes--Glycerate Kinase 1 (GLYCTK1) and its alternatively splicing variant--Glycerate Kinase 2 (GLYCTK2), which might be associated with D-glycerate acidemia/D-glyceric aciduria. The locus of GLYCTK gene is mapped to 3p21. PCR amplification in seventeen human tissue cDNAs revealed that both GLYCTK1 and GLYCTK2 are expressed widely almost in all these tissues. The expression of mouse Glyctk in various tissues was demonstrated by in situ hybridization. Both GLYCTK1 and GLYCTK2 proteins are localized in cytosol, and GLYCTK2 proteins are specifically localized in mitochondria. Present results revealed the characteristic expression pattern of murine Glyctk in neural system, skeleton muscle, supporting that glycerate kinase is implicated in D-glycerate acidemia/D-glyceric aciduria.

Alternative Splicing↗
PubMed2006

Antisense oligonucleotide targeting p53 increased apoptosis of MCF-7 cells induced by ionizing radiation.

AIM: To investigate the effect of antisense compounds (AS) targeting human p53 mRNA on radiosensitivity of MCF-7 cells. METHODS: Western blotting and RTPCR were used to analyze the protein content and mRNA level. Additionally, cell proliferation, cell cycle and cell apoptosis were all analyzed in irradiated or sham-irradiated cells. RESULTS: Among the five antisense compounds (AS), AS3 was identified to efficiently inhibit p53 mRNA level and protein content. Interestingly, AS3 transfer has little effect on cell proliferation in DU-145 cells (mutant p53) after ionizing radiation (IR). In contrast, a marked increase of cell apoptosis and growth inhibition were observed in MCF-7 cells (wild-type p53), suggesting that AS3 can increase radiosensitivity of MCF-7 cells. Additionally, it was also observed that the transfection of AS3 decreased the fraction of G1 phase cells, and increased the proportion of S phase cells compared to untreated cells 24 h after IR in MCF-7 cell lines. CONCLUSION: AS3 transfection increases MCF-7 cell apoptosis induced by 5 Gy-radiation, and this mechanism may be closely associated with abrogation of G1 phase arrest.

Apoptosis↗
PubMed2006

Antisense oligonucleotides targeting midkine induced apoptosis and increased chemosensitivity in hepatocellular carcinoma cells.

AIM: Overexpression of midkine (MK) has been observed in many malignancies. This aim of this study is to screen for suitable antisense oligonucleotides (ASODN) targeting MK in hepatocellular carcinoma (HCC) cells and evaluate its antitumor activity. METHODS: Ten ASODN targeting MK were designed and synthesized. After transfection with ASODN, cell proliferation was analyzed with MTS[3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt] assay. In addition, MK mRNA, protein levels, as well as apoptosis and caspase-3 activity were also examined in HepG2 cells. Cell proliferation was then analyzed after treatment with both ASODN and chemotherapeutic drugs. RESULTS: In this experiment, the ASODN5 among the 10 ASODN showed higher inhibitory activity against proliferation of hepatocellular carcinoma cells in a dose-dependent manner. In HepG2 cells, ASODN5 could significantly reduce the MK mRNA level and protein content. After transfection with ASODN5 for 48 h, accompanied with a decline of survivin and Bcl-2 protein content, a remarkable increase of apoptosis and caspase-3 activity was observed in HepG2 cells. Furthermore, ASODN5 transfer can significantly increase chemosensitivity in HepG2 cells. CONCLUSION: Antisense oligonucleotides targeting MK shows therapeutic effects on HCC; ASODN5 has the possibility to be developed as an effective antitumor agent.

Antimetabolites, Antineoplastic↗
PubMed2006

[Advances in xenogeneic transplantation of spermatogonial stem cell and its bewilderment in clinical application].

Results from the transplantation of donor spermatogonia into xenogeneic recipient seminiferous tubules indicate that donor germ cells are capable of differentiating to form spermatozoa with morphological character of the donor species. With the advances in freezing, culturing in vitro and enriching germ cell populations, germ cell transplantation procedures have applications of paramount values in medicine, basic science and animal reproduction. Additionally, these techniques can serve as an alternative approach for gonadal protection and fertility preservation especially in patients accepting large dose of chemotherapy or radiotherapy. In this article we reviewed the recent advances in xenogeneic transplantation of spermatogonial stem cell and also analyzed the potential problems existing in its clinical application.

Animals↗
PubMed2006

[Clinical application of video-assisted thoracoscopic surgery].

OBJECTIVE: To explore the clinical application of video-assisted thoracoscopic surgery (VATS). METHODS: We retrospectively analyzed the clinical data of 672 cases of VATS. There were 17 thoracic diseases such as emphysema, bullectomy for spontaneous pneumothorax, massive bullae, benign tumor of mediastinum, cyst of mediastinum, pulmonary benign tumors, hydropericardium, malignant pleural fluid, etc. RESULTS: The mean operation time was 57 minutes and there were no intraoperative complications. The bleeding during the operation was less than 100 mL. Postoperative pneumothorax occurred in 4 patients and among them 2 patients were of relapse after 1 month. The intrathoracic drain in most patients was removed with an average of 2. 5 days. A supplementary incision was needed in 10 cases: Six were due to the adhesion of full pleural cavity and 4 were found with the malignant tumor during the operation. CONCLUSION: VATS is an alternative approach that provides a safe, less invasive, and effective operation for treating spontaneous pneumothorax, benign tumor of mediastinum, cyst of mediastinum, pulmonary benign tumors, pericardial perfusion, and acute chest trauma patients.

Adolescent↗
PubMed2006

[Experimental study on a novel affinity adsorbent for removal of endotoxin in plasma].

In this paper, the adsorbent properties of Polymyxin B immobilized polystyrene microbeads to remove endotoxin from plasma were studied and the factors that affected the absorption of endotoxin were discussed. The rat models of endotoxemia were established, which were used in hemoperfusion. The experiment results indicated that the novel affinity adsorbent could remove endotoxin from plasma effectively. Moreover, the results also showed that Polymyxin B immobilized polystyrene microbeads was a fine biomaterial of hemoperfusion as well as exhibited a satisfactory blood compatibility.

Adsorption↗
PubMed2005

[Immediate breast reconstruction with DIEP flap following modified radical mastectomy].

OBJECTIVE: To review the experience in immediate breast reconstruction with DIEP flap following modified radical mastectomy. METHODS: From 2003 to 2005, eight patients with breast cancer have undergone modified radical mastectomy and immediate breast reconstruction with deep inferior epigastric perforator flap. Six patients had stage I disease and 2 patients had stage II disease. RESULTS: The flaps in all the cases survived. Two occurred minor complications. A small part of venous congestion occurred in one flap. One patient had hematoma under the flap. Follow up more than 6 months, no evidence of recurrence and metastasis occurs. Postoperative abdominal wall examination didn't reveal and hernia and bulging. Patient satisfaction with the reconstructed breast was rated high. The reconstructed breast achieved good results in shape, colour and symmetry. CONCLUSION: The procedure introduced is an ideal method for breast reconstruction after modified radical mastectomy.

Adult↗
PubMed2005

Fhit and CHK1 have opposing effects on homologous recombination repair.

Fragile histidine triad (FHIT) gene deletion or promoter methylation and reduced Fhit protein expression occur in approximately 70% of human epithelial tumors and, in some cancers, are clearly associated with tumor progression. Specific Fhit signal pathways have not been identified. We previously reported that compared with Fhit+/+ cells, Fhit-/- cells with an overactivated ATR/CHK1 pathway show increased mutation frequency and resistance to DNA damage-induced killing, indicating that Fhit and the CHK1 pathway have opposing roles in cells responding to DNA damage. In this study, we show that cells, with or without Fhit expression, have similar DNA double-strand break induction levels and similar rejoining rates following ionizing radiation, indicating that the effect of Fhit on cell radiosensitivity is independent of nonhomologous end-joining. By combining I-SceI-induced-DNA double-strand break system and small interfering RNA approach, we also show that knocking down Fhit increases the efficiency of homologous recombination repair of cells, but knocking down Chk1 decreases the efficiency of homologous recombination repair, associated with the sensitivity to ionizing radiation-induced killing. Taken together, the results show that the role of Fhit in affecting the sensitivity of cells to ionizing radiation-induced killing is through the CHK1 pathway linked to homologous recombination repair. These results also illustrate the importance of balanced checkpoint activation in genomic stability and suggest a connection between the radioresistance and mutagenesis, carcinogenesis, as well as tumor progression in Fhit-deficient cells or tissue.

Acid Anhydride Hydrolases↗
PubMed2005

Contrast-enhanced ultrasonographic imaging diagnosis on assessment of vascularity in liver metastatic lesions.

AIM: To investigate the vasculature of rabbit liver metastatic lesions by color Doppler imaging and power Doppler imaging (PDI) techniques. METHODS: Eight New Zealand rabbits with implanted VX2 liver tumors were used. All ultrasound examinations were performed with a HP 5500 color Doppler ultrasound scanner. Before and after the injection of contrast agent, the changes of gray scale and the periphery and intralesional blood flow of the liver metastatic lesion were carefully observed by B mode ultrasound, color Doppler flow imaging (CDFI) and PDI. RESULTS: Twelve lesions were found in the eight rabbits with implanted VX2 liver tumors, whose diameter ranged from 1.6 to 4.8 cm. Echoes of these lesions were not characterized and has lack of specificity. After the injection of contrast agent, the numbers of dot or strip-like flow messages increased both at the periphery and inside of these lesions under the mode of CDFI and PDI, and were more pronounced under PDI. Morphology of intralesional vessels extended, even branched and some signals were clearly found encircling the lesion. And some vessels were found penetrating into the center of the lesion. CONCLUSION: PDI after injection of self-made echo contrast agent can show a pronounced sensitivity than that of B mode ultrasound and CDFI in diagnosis of vascularity of a metastatic lesion.

Animals↗
PubMed2005

The value and limitation of transcatheter arterial chemoembolization in preventing recurrence of resected hepatocellular carcinoma.

AIM: To evaluate the value and limitation of postoperative transcatheter arterial chemoembolization (TACE) in preventing recurrence of hepatocellular carcinoma (HCC). METHODS: In the first group, 987 postoperative patients with HCC, who did not have any evidence of recurrence in the first preventative TACE but were found to have recurrence at different times during the follow-up survey, were analyzed. In the second group, 643 postoperative patients with HCC had no TACE for compared study. To study the relationship between the recurrence time and the number of TACE treatments was analyzed. RESULTS: The 6-, 12-, and 18-mo recurrence rates in the first and second groups were 22.2% (210 cases) vs 61.6% (396 cases), 78.0% (770 cases) vs 74.7% (480 cases) and 88.6% (874 cases) vs 80.1% (515 cases). There were significant differences between the recurrence rates of the two groups at 6 mo (P<0.0001). CONCLUSION: The principal role of TACE after HCC operation is to suppress, detect early and treat micro-metastasis. It has a good effect of preventing recurrence of HCC in 6 mo, but such an effect is less satisfactory in a longer period. When it is uncertain whether HCC is single-central or multi-central and if there is cancer residue or metastasis after operation, TACE is valuable to prevent recurrence.

Carcinoma, Hepatocellular↗
PubMed2005

T helper cell related interleukins and the angiographic morphology in unstable angina.

Angiographically visible complex lesions, associated with disrupted plaques and intraluminal thrombus, are more common in unstable angina (UA). The aim of our study was to evaluate the relationship between the complex lesions and the T helper cells related Interleukins (IL). We analyzed the concentrations of IL-10, IL-12, IL-18 using ELISA and that of hsCRP using Latex particle enhanced Immunoturbidimetry in 50 patients of UA. Thirty-one of these patients had complex lesions and 19 had simple lesions as visible during coronary angiography. We further compared them with 30 control subjects having no evidence of coronary artery diseases. The levels of IL-12 in patients having complex lesions tended to be higher than in those having simple lesions and levels of IL-10 tended to be lower in the former than the latter, but the differences were not statistically significant. The patients with complex lesions showed significantly higher concentrations of IL-18 as compared to those having simple lesions. Furthermore, IL-18 was found to be independent predictor for the complex lesion morphology in UA patients. These findings suggest that disrupted plaques and intraluminal thrombus, angiographically visible as complex lesions are associated with increased concentrations of T helper 1 cell related interleukins, mainly IL-18, and IL-18 being a possible bio-marker for risk stratification in UA.

Angina, Unstable↗
PubMed2005

Direct C-arylation of free (NH)-indoles and pyrroles catalyzed by Ar-Rh(III) complexes assembled in situ.

Ar-Rh(III) pivalate complexes assembled in situ from the reaction of [RhCl(coe)2]2 (coe = cis-cyclooctene), [p-(CF3)C6H4]3P, and CsOPiv effectively catalyzed the direct C-arylation of free (NH)-indoles and (NH)-pyrroles in good yields and with high regioselectivity. The reaction displayed excellent functional group compatibility and low moisture sensitivity. Kinetics studies support a mechanism involving phosphine displacement by indole in complex 2 (resting state of the catalyst), followed by a rate-limiting C-H bond metalation.

Journal Article↗