Biomedical subjects

Tong Wang

Publications and source records attributed to Tong Wang.

82 records · Page 5Linked to original sources

PubMed2003

[Advances in studies on flavonoids of licorice].

The progress in the research of the active ingredients of licorice flavonoid and the pharmacological activities was reviewed. Licorice flavonoid constituents mainly included flavones, flavonals, isoflavones, chalcones, bihydroflavones and bihydrochalcones. Pharmacological investigation concluded that they had antioxidant, antibacterial, antitumer and inhibiting HIV activities. It is important to study further the flavonoid constituents and pharmacological activities.

Animals↗

PubMed2002

Absence of small conductance K+ channel (SK) activity in apical membranes of thick ascending limb and cortical collecting duct in ROMK (Bartter's) knockout mice.

The ROMK (Kir1.1; Kcnj1) gene is believed to encode the apical small conductance K(+) channels (SK) of the thick ascending limb (TAL) and cortical collecting duct (CCD). Loss-of-function mutations in the human ROMK gene cause Bartter's syndrome with renal Na(+) wasting, consistent with the role of this channel in apical K(+) recycling in the TAL that is crucial for NaCl reabsorption. However, the mechanism of renal K(+) wasting and hypokalemia that develop in individuals with ROMK Bartter's syndrome is not apparent given the proposed loss of the collecting duct SK channel. Thus, we generated a colony of ROMK null mice with approximately 25% survival to adulthood that provides a good model for ROMK Bartter's syndrome. The remaining 75% of null mice die in less than 14 days after birth. The surviving ROMK null mice have normal gross renal morphology with no evidence of significant hydronephrosis, whereas non-surviving null mice exhibit marked hydronephrosis. ROMK protein expression was absent in TAL and CCD from null mice but exhibited normal abundance and localization in wild-type littermates. ROMK null mice were polyuric and natriuretic with an elevated hematocrit consistent with mild extracellular volume depletion. SK channel activity in TAL and CCD was assessed by patch clamp analysis in ROMK wild-type ROMK(+/+), heterozygous ROMK(+/-), and null ROMK(-/-) mice. In 313 patches with successful seals from the three ROMK genotypes, SK channel activity in ROMK (+/+ and +/-) exhibited normal single channel kinetics. The expression frequencies are as follows: 67 (TAL) and 58% (CCD) in ROMK(+/+); about half that of the wild-type in ROMK(+/-), being 38 (TAL) and 25% (CCD); absent in both TAL or CCD in ROMK(-/-) between 2 and 5 weeks in 15 mice (61 and 66 patches, respectively). The absence of SK channel activity in ROMK null mice demonstrates that ROMK is essential for functional expression of SK channels in both TAL and CCD. Despite loss of ROMK expression, the normokalemic null mice exhibited significantly increased kaliuresis, indicating alternative mechanisms for K(+) absorption/secretion in the nephron.

Aging↗

PubMed2002

Reversible stretching of a monomeric unit in a dimeric bovine carbonic anhydrase B with the atomic force microscope.

We have previously shown that a full stretching of native carbonic anhydrase B (CAB) using the atomic force microscope could not be achieved, presumably due to the presence of a 'knot' in the C-terminal region of the protein. When we used an engineered dimer of CAB, where the N-terminal monomeric unit (unit I) was expected to be 'knotless', we successfully recorded extension of the protein up to 110 nm which was long enough to account for the full extension of unit I monomer. In this paper we report that, by limiting the maximum length of extension to 90 nm extensions (corresponding to about 80 nm extension of the dimer and 70 nm of unit I), retractions of the polypeptide chain can be repeated cyclically without breaking the covalent crosslinking system. The force-extension curves obtained from the forward and reverse cycles of such experiments were almost perfectly superimposable with each other and with the corresponding part of the curves obtained from full extension experiments suggesting that the structure of unit I in the dimer was reversibly stretched and contracted. During the stretching of unit I of the dimer in either type of the experiments mentioned above, we occasionally observed a force peak having the force of about 0.5-0.7 nN when extension length reached 40-50 nm. We interpreted the appearance of such force peaks as an indication of formation of a tightly folded domain structure in unit I of CAB dimer.

Animals↗

PubMed2002

Formate-stimulated NaCl absorption in the proximal tubule is independent of the pendrin protein.

A significant fraction of active chloride reabsorption across the apical membrane of the proximal tubule is mediated by a chloride/formate exchange process, whereby intracellular formate drives the transport of chloride into the cell. When chloride/formate exchange operates in parallel with Na(+)/H(+) exchange and H(+)-coupled recycling of formate, the net result is electroneutral NaCl reabsorption. Pendrin is the protein product of the PDS gene (SLC26A4) and functions in several different anion exchange modes, including chloride/formate exchange. Pendrin is expressed in the kidney and may serve as the transporter responsible for formate-dependent NaCl reabsorption. In the present study, Pds-knockout mice were used to determine the role of pendrin in proximal tubule chloride reabsorption. We show that formate-dependent NaCl absorption in microperfused proximal tubules is similar between wild-type and pendrin-deficient mice. In addition, there is no difference in the rate of formate-mediated chloride transport in brush-border membrane vesicles isolated from wild-type and pendrin-deficient mice. These studies demonstrate that pendrin is not responsible for formate-dependent NaCl reabsorption in the proximal tubule.

Animals↗

PubMed2002

Role of iNOS and eNOS in modulating proximal tubule transport and acid-base balance.

Our laboratory has previously shown that mice lacking neuronal nitric oxide synthase (nNOS) are defective in fluid absorption (J(v)) and HCO absorption (J(HCO3)) in the proximal tubule and develop metabolic acidosis. The present study examined the transport of fluid and HCO in the proximal tubule and acid-base status in mice lacking two other isoforms of NOS, inducible NOS (iNOS) and endothelial NOS (eNOS). Proximal tubules were microperfused in situ in wild-type and NOS knockout mice by methods previously described (Wang T, Yang C-L, Abbiati T, Schultheis PJ, Shull GE, Giebisch G, and Aronson PS. Am J Physiol Renal Physiol 277: F298-F302, 1999). [(3)H]inulin and total CO(2) concentrations were measured in the perfusate and collected fluid, and net J(v) and J(HCO3) were analyzed. These data show that J(HCO3) was 35% lower (71.7 +/- 6.4 vs. 109.9 +/- 7.3 pmol x min(-1) x mm(-1), n = 13, P < 0.01) and J(v) was 38% lower (0.95 +/- 0.15 vs. 1.54 +/- 0.17 nl. min(-1) x mm(-1), n = 13, P < 0.05) in iNOS knockout mice compared with their wild-type controls. Addition of the iNOS-selective inhibitor L-N(6)-(1-iminoethyl) lysine, reduced both J(v) and J(HCO3) significantly in wild-type, but not in iNOS knockout, mice. In contrast, both J(HCO3) (93.3 +/- 7.9 vs. 110.6 +/- 6.18 pmol x min(-1) x mm(-1)) and J(v) (1.56 +/- 0.17 vs. 1.55 +/- 0.16 nl. min(-1) x mm(-1)) did not change significantly in eNOS knockout mice. These results indicated that iNOS upregulates Na(+) and HCO transport, whereas eNOS does not directly modulate Na(+) and HCO transport in the kidney proximal tubules.

Absorption↗

PubMed2002

The effect of calmodulin antagonist berbaminederivative-EBB on hepatoma in vitro and in vivo.

OBJECTIVE: To evaluate the anti-hepatoma effect of Calmodulin antagonist 0 - 4-ethoxyl-butyl-Berbamine (EBB), one of the berbamine derivatives. METHODS: Monotetrazolium (MTT) method was used to analyze the effect of EBB on the proliferation and growth inhibition effect. Of a hepatoma cell line in vitro. A mouse hepatoma model was induced by injection of hepatoma cells (H22) in the abdominal cavity. The effect of EBB on survival at different concentrations as well as in combination with 5-FU were investigated in vivo. Flow cytometry analysis, dot blot hybridization, western blot, immunochemistry, enzyme-linked lectin assay (ELISA), trifluoperazine (TFP) and electron microscopic observation were used to study the effect of EBB on cell cycle process, P53 mRNA and protein levels, calmodulin content and ultrastractural changes of hepatoma cells. RESULTS: EBB exerts a very strong inhibitory effect on human hepatoma cell line 7402 and mouse hepatoma cell line H22 in vitro. The IC(50) value of EBB for the two cell lines are 3.312 microg/ml and 1.167 microg/ml, respectively. The sensitivity of H22 cells to 5-FU can be markedly enhanced: The IC(50) dosage of 5-Fu can be decreased from 0.75 microg/ml down to 0.15 microg/ml, when jointly administered with nontoxic dosages of EBB (IC(10)). In vivo, EBB can prolong the lifespan of mice with ascites H22 to more than three months. 64% of mice survived, while all animals in the control group died by the 18th day. When EBB (5 mg x kg(-1) x d(-1)) is jointly used with 5-FU (25 mg x ml(-1) x d(-1)), 73% of mice with ascites H22 survived, much higher than 27% in the 5-FU treated group. EBB can enhance the anti-hepatoma ability of 5-Fu treatment. EBB mechanism against hepatoma: P53 expression in the EBB treated group is substantially higher than that in the control group. EBB increased the translation of P53. As a calmodulin antagonist, EBB decreases amount of the CaM in hepatoma cells and blocked the hepatoma cell proliferation cycle at the G(2)M phase. Before the G(0)/G(1) phase, a diploid peak and apoptic cells in the treated groups were observed. CONCLUSIONS: The CaM antagonist, EBB, has a strong anti-hepatoma effect and enhances the effect of 5-FU, induces hepatoma cell to apoptosis, promotes the P53 protein expression and decreases the amount of CaM in the cytoplasm. All these results demonstrate that EBB is a new and potentially useful drug against hepatoma and should be researched further.

Alkaloids↗

PubMed2002

Serum-free culture of dendritic cells from patients with chronic myeloid leukemia in vitro and estimation of their cytotoxicity.

OBJECTIVE: To establish a serum-free culture system of dendritic cells (DCs) from chronic myeloid leukemia (CML) cells so that DCs vaccine may be applied to the adoptive immunotherapy of CML in the near future. METHODS: Fetal calf serum, serum-free medium and autologous serum were used for culture of DCs. The usage of cytokines was classified into two groups: group A (stem cell factor, granulocyte/macrophage colony-stimulating-factor, tumor necrosis factor-alpha and interleukin-4) and group B (granulocyte/macrophage colony-stimulating-factor, tumor necrosis factor-alpha and interleukin-4). The phenotypes of DCs were analyzed by using indirect immunofluorescence and flow cytometry. Mixed leukocyte responses were performed by methyl thiazolyl tetrazolium (MTT) assay. Chromosome analysis of DCs can be achieved by displaying G banding. T cells from CML patients were stimulated with autologous DCs and T-cell cytotoxicity was measured by (MTT) assay. RESULTS: CD34(+) cells or mononuclear cells were obtained from peripheral blood or bone marrow samples of eight patients of chronic-phase CML. Group A of serum-free medium was better than group B in expansion of total cell numbers and the rate of DCs. These results of serum-free medium were not significantly different from those of fetal calf serum medium, but the results of autologous serum medium were inferior to two groups above. The expression of major histocompatibility complex class II antigen on the surface of DCs was notable (> 50%), but the expression of CD83 and the costimulatory molecules CD86 was not noticeable (10% - 50%). Although CD1a(+)/CD14(-) DCs were potent stimulators of allogeneic lymphocytes, expansion of T cells from normal volunteers were not significant (average 27.2 fold at DCs: T cells ratio of 1:10). At day 12, CD1a(+) cells from three patients were studied by displaying G banding and Ph(+) cells in these populations were 100%, 98% and 60%, respectively. At an effector: target ratio of 40:1, 32% to 45% cytotoxicity was noted with DC-stimulated T cells against autologous leukemia cells. CONCLUSIONS: A stable serum-free culture system of CML-DCs was established. The expression of CD83 and CD86 on the surface of CML-DCs and DCs' potent stimulation of allogeneic lymphocytes were not notable. DCs in CML patients can be derived from the malignant clone and these malignant DCs could induce anti-leukemic reactivity in autologous T lymphocytes without the necessity for additional exogenous antigens.

Cells, Cultured↗

PubMed2002

The directionality of share adhesive strength between composite resin and dental hard tissue.

OBJECTIVE: To inspect the directionality of adhesive strength between composite resins and dental hard tissues. METHODS: Two kinds of composite resins were bonded with their luting kits to the enamel and dentin surfaces of bovine teeth separately. The dead load shear and impact shear testing were performed from both of root apex direction and cutting edge direction. RESULTS: The shear adhesive strength between the enamel and two kinds of composite resins was on the same behavior, that the shear adhesive strength of root apex direction was greater than that of cutting edge direction. In the dead load shear testing, the former was about two to three times of the latter (P < 0.05). In the impact shear testing, the former was about three to four times of the latter (P < 0.001). The effect of the direction of acting force was small on the shear adhesive strength between the dentin and two kinds of composite resins. In the both dead load shear testing and impact shear testing, there was no statistically significant difference between the datum of two directional loadings (P > 0.05, P > 0.5). CONCLUSION: The shear adhesive strength between the composite resins and enamel of bovine teeth is related to the acting direction of the shear force.

Adhesiveness↗

PubMed2002

[Expression of p53 and vascular endothelial growth factor in esophageal squamous cell carcinoma and their clinical significance].

BACKGROUND & OBJECTIVE: Experimental study proved that the coexpression of p53 and vascular endothelial growth factor (VEGF) play an important role in angiogenesis of tumor. The aim of this study was to investigate the mechanism that p53 participate angiogenesis and the relationship between the expression of p53 and VEGF and clinical pathologic parameters and prognosis of esophageal squamous cell carcinoma (ESCC). METHODS: The expressions of p53 and VEGF in operative samples from 76 ESCC patients were detected by immunohistochemistry. The vascular endothelial cells in tumor tissue were labeled by F VIII factor antibody for counting microvessel density (MVD). RESULTS: The expression rates of p53 and VEGF were 60.5% and 56.5%; total expression rate was 42.1%. The expression rates of p53 and VEGF were strongly associated with distal metastasis and vascular infiltration of ESCC (P < 0.05, P < 0.01). Distal metastasis and vascular infiltration usually occurred in the patients whose mutant p53 and VEGF were both positive expression. The MVDs in p53(+) or VEGF(+) (31.7 +/- 11.5; 33.8 +/- 11.7) were both significantly higher than that in p53(-) or VEGF(-) (22.4 +/- 10.6; 21.2 +/- 9.3, P < 0.05). The MVD reached the maximum in the patients whose p53 and VEGF were both positive. CONCLUSION: Mutant p53 expression is closely associated with the angiogenesis and distal metastasis of ESCC; Expression of p53 and VEGF could be used as an important biological indices for evaluating the malignant degree of ESCC. Combined determination of p53 and VEGF expression has important clinical significance.

Adult↗

PubMedDate not supplied

Use of transgenic animals to study renal acid-base transport.

Many of the transporters mediating renal acid-base homeostasis have recently been identified at the molecular level. These advances have made it possible to generate transgenic mice with deficiency or overexpression of specific transporter isoforms. Such knockout mice have served as useful experimental models to quantitate the contribution of a given transporter isoform to transtubular acid-base transport along the nephron. Studies with transgenic and knockout mice have also been used to elucidate the compensatory adaptive mechanisms in response to specific transport deficiencies. We review experiments using transgenic mice to evaluate the physiological roles in acid-base transport of NHE isoforms, vacuolar H+ pump subunits, H+, K(+)-ATPase isoforms, carbonic anhydrase, Cl(-)-base exchangers and such regulatory mediators as nitric oxide and endothelin.

Acid-Base Equilibrium↗