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X D Zhang

Publications and source records attributed to X D Zhang.

At least 37 records · Page 2Linked to original sources
PubMed2001

How melanoma cells evade trail-induced apoptosis.

At the doses used clinically, chemotherapy is believed to kill melanoma by a final common 'mitochondrial' pathway that leads to apoptosis. Similarly, several natural defence mechanisms kill melanoma by the same pathways. A corollary to the latter is that survival of melanoma in the host is due to the development of anti-apoptotic mechanisms in melanoma cells. What are these mechanisms? And how might we bypass them to improve the treatment of melanoma?

Animals↗
PubMed2001

[Studies of FISH and karyotype of Gossypium barbadense].

Based on the fluorescent in situ hybridization (FISH) of somatic chromosome of Gossypium barbadense with the probe of genomic DNA (gDNA) of Gossypium arboreum, two sets of chromosomes were easily distinguished by signals hybridized or not. The FISH directly proved that G. barbadense originated from two different diploid species, but was not in concordance with the former point that every chromosome of A sub-genome of tetraploid species was bigger than that of other sub-genome (D genome). The karyotype formula of G. barbadense based on its FISH was 2n = 4x = 52 = 38 m + 14sm(6sat). There were three pairs of satellite chromosomes which were all sm types. Their satellites located in short arms but originated differently from their chromosomes of sub-genome. Fragment translocations occured in the long arms of homologous chromosomes of number 5, 6 and 9 of A sub-genome. It was suggested that the translated fragments come from D sub-genome. The fragments are fairly large with the relative lengths of 19.21%, 17.69% and 12.88% of their whole chromosomes, respectively. At least five pairs of chromosomes in D sub-genome show some hybridized signals of gDNA probe of G. arboreum in their centromere regions, which indicated that there would be chromatin introgressions from A sub-genome.

Gossypium↗
PubMed2001

Relative resistance of fresh isolates of melanoma to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis.

In previous studies, we have shown that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) could induce varying degrees of apoptosis in approximately two-thirds of human melanoma lines. In the present study, we have examined the sensitivity of fresh isolates and early passages of melanoma cells to TRAIL-induced apoptosis from eight patients. We found that fresh isolates were relatively resistant to TRAIL-induced apoptosis and that this appeared to be associated with low TRAIL death receptor (TRAIL-R) expression. TRAIL-R expression was also undetectable in tissue sections from the same melanoma. We attempted to create a model for these findings by generation of TRAIL-resistant melanoma lines from TRAIL-sensitive lines grown for prolonged periods in TRAIL. The resulting TRAIL-resistant melanoma cell lines had low TRAIL-R expression, and sensitivity to TRAIL was increased rapidly by pretreatment with proteasome inhibitors known to inhibit activation of nuclear factor-kappaB. However, the latter treatment had no significant effect on the sensitivity of fresh isolates to TRAIL. The levels of the inhibitors of apoptosis, Flice-like inhibitory protein and Bcl-2, also did not relate to resistance to TRAIL-induced apoptosis. These results suggest that down-regulation of TRAIL-R on melanoma cells may be the primary determinant of resistance of fresh isolates to TRAIL, and the basis for this requires further investigation.

Antibodies, Monoclonal↗
PubMed2001

Effects of erysimin G on renal tubular function and 70-pS K+ channel activity of thick ascending limb.

AIM: To study the effect of erysimin G (CH35H52O13) on the thick ascending limb (TAL) 70-pS K+ channel of rat kidney and its effect on diuresis. METHODS: The patch-clamp cell-attached recording technique was used to record the single potassium channel current, and the urine volume (UV) was measured by urethral intubation to determine the diuretic effect. RESULTS: Erysimin G can increase the urine volume and decrease the 70-pS potassium channel activity of TAL. CONCLUSION: Erysimin G has a diuretic effect and its inhibition on the activity of apical 70-pS potassium channel may be the mechanism of its diuretic effect.

Animals↗
PubMed2000

TNF-related apoptosis-inducing ligand-induced apoptosis of melanoma is associated with changes in mitochondrial membrane potential and perinuclear clustering of mitochondria.

Past studies have shown that TNF-related apoptosis-inducing ligand (TRAIL) induced apoptosis in a high proportion of cultured melanoma by caspase-dependent mechanisms. In the present studies we have examined whether TRAIL-induced apoptosis of melanoma was mediated by direct activation of effector caspases or whether apoptosis was dependent on changes in mitochondrial membrane potential (MMP) and mitochondrial-dependent pathways of apoptosis. Changes in MMP were measured by fluorescent emission from rhodamine 123 in mitochondria. TRAIL, but not TNF-alpha or Fas ligand, was shown to induce marked changes in MMP in melanoma, which showed a high correlation with TRAIL-induced apoptosis. This was associated with activation of proapoptotic protein Bid and release of cytochrome c into the cytosol. Overexpression of B cell lymphoma gene 2 (Bcl-2) inhibited TRAIL-induced release of cytochrome c, changes in MMP, and apoptosis. The pan caspase inhibitor z-Val-Ala-Asp-fluoromethylketone (zVAD-fmk) and the inhibitor of caspase-8 (z-Ile-Glu-Thr-Asp-fluoromethylketone; zIETD-fmk) blocked changes in MMP and apoptosis, suggesting that the changes in MMP were dependent on activation of caspase-8. Activation of caspase-9 also appeared necessary for TRAIL-induced apoptosis of melanoma. In addition, TRAIL, but not TNF-alpha or Fas ligand, was shown to induce clustering of mitochondria around the nucleus. This process was not essential for apoptosis but appeared to increase the rate of apoptosis. Taken together, these results suggest that TRAIL induces apoptosis of melanoma cells by recruitment of mitochondrial pathways to apoptosis that are dependent on activation of caspase-8. Therefore, factors that regulate the mitochondrial pathway may be important determinants of TRAIL-induced apoptosis of melanoma.

Amino Acid Chloromethyl Ketones↗
PubMed2000

Mechanisms of resistance of normal cells to TRAIL induced apoptosis vary between different cell types.

Resistance of normal cells to tumour necrosis factor related apoptosis inducing ligand (TRAIL) induced apoptosis is believed to be mediated by expression of two decoy receptors. Here we show that the expression and localisation of TRAIL receptors (TRAIL-Rs) vary between different cells and that resistance to TRAIL is mediated by different mechanisms. The decoy receptor, TRAIL-R3, appeared important in protection of endothelial cells, whereas lack of surface death receptor expression and as yet unknown intracellular inhibitor(s) of apoptosis downstream of caspase-3 may play a major role in protection of melanocytes and fibroblasts from TRAIL induced apoptosis, respectively. Differential subcellular location of decoy receptors may be an important determinant of their effectiveness in different types of normal cells.

Apoptosis↗
PubMed2000

Differential localization and regulation of death and decoy receptors for TNF-related apoptosis-inducing ligand (TRAIL) in human melanoma cells.

Induction of apoptosis in cells by TNF-related apoptosis-inducing ligand (TRAIL), a member of the TNF family, is believed to be regulated by expression of two death-inducing and two inhibitory (decoy) receptors on the cell surface. In previous studies we found no correlation between expression of decoy receptors and susceptibility of human melanoma cells to TRAIL-induced apoptosis. In view of this, we studied the localization of the receptors in melanoma cells by confocal microscopy to better understand their function. We show that the death receptors TRAIL-R1 and R2 are located in the trans-Golgi network, whereas the inhibitory receptors TRAIL-R3 and -R4 are located in the nucleus. After exposure to TRAIL, TRAIL-R1 and -R2 are internalized into endosomes, whereas TRAIL-R3 and -R4 undergo relocation from the nucleus to the cytoplasm and cell membranes. This movement of decoy receptors was dependent on signals from TRAIL-R1 and -R2, as shown by blocking experiments with Abs to TRAIL-R1 and -R2. The location of TRAIL-R1, -R3, and -R4 in melanoma cells transfected with cDNA for these receptors was similar to that in nontransfected cells. Transfection of TRAIL-R3 and -R4 increased resistance of the melanoma lines to TRAIL-induced apoptosis even in melanoma lines that naturally expressed these receptors. These results indicate that abnormalities in "decoy" receptor location or function may contribute to sensitivity of melanoma to TRAIL-induced apoptosis and suggest that further studies are needed on the functional significance of their nuclear location and TRAIL-induced movement within cells.

Amino Acid Chloromethyl Ketones↗
PubMed2000

[Effects of bFGF and BDNF on the cells of injured adult mouse olfactory epithelium in vitro].

Olfactory epithelium (OE) is unique in the adult nervous system for it produces new neurons throughout life. The cultured cells of adult mouse OE in vitro were studied by histochemistry and immunocytochemistry techniques, and the results showed that they were neurons as up to 50% of the bipolar cells were immunopositive to NF, NSE, MAP2, OMP and tau. The effects of basic fibroblast growth factor (bFGF) and brain-derived neurotrophic factor (BDNF) in OE medium with different concentration serum on OE cell number and development of cell processes were also observed. The results showed that the combination of bFGF and BDNF added to 10% and 5% serum OE medium increased the bipolar cell number and percentage, stimulated the process outgrowth of bipolar cells, and decreased the numbers of giant cells and fusiform cells. The effects of the combination of bFGF and BDNF in the 10% serum OE medium were more significant than those of bFGF and BDNF applied alone; and the effects of neurotrophic factors in the 10% serum OE medium were more significant than those observed in the 5% serum OE medium.

Animals↗
PubMed1999

Microemulsion electrokinetic chromatography of proteins.

Microemulsion electrokinetic chromatography was used to separate a test mixture of proteins effectively. The separation was carried out in a 42.5 cm (to the detector) x 50 microns I.D. fused-silica capillary using a microemulsion system consisting of 80 mM heptane, 120 mM SDS, 900 mM butanol in 2.5 mM borate buffer, pH 8.5-9.5. Optimum separation conditions were investigated with respect to the running voltage, temperature, pH and the composition of microemulsion. Results were compared with those obtained in micellar electrokinetic chromatography and capillary zone electrophoresis. The examined method is practical and successfully applied to the assay of genetically engineering pharmaceuticals, recombinant human granulocyte macrophage colony stimulating factor injection and recombinant human granulocyte colony stimulating factor injection.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed1999

Binding of the potent allergen hexahydrophthalic anhydride in the mucosa of the upper respiratory and alimentary tract following single inhalation exposures in guinea pigs and rats.

Hexahydrophthalic anhydride (HHPA; CAS No. 13149-00-3) is a highly allergenic compound commonly used in the chemical industry. Guinea pigs and rats were exposed to [3H2]HHPA by inhalation for 3-8 h and were killed at various intervals during 7 days. The tissue distribution of non-volatile and covalently bound radioactivity was studied by autoradiography. Tissue bound radioactivity was mainly found in the mucosa of the upper respiratory airways, whereas negligible levels were observed in the lungs. In addition, tissue bound radioactivity was present in the gastrointestinal tract and conjunctiva. Moreover, in the cortex of the kidneys in rats, but not in guinea pigs, a low level of tissue bound radioactivity was found. The radioactivity in the tissues persisted for at least 7 days after the end of exposure. Plasma proteins and soluble proteins from trachea, lung, and kidney from [3H2]HHPA-exposed animals were separated by gel filtration. The radioactivity in dialysed plasma was mainly found in the same fractions as albumin. The soluble proteins from trachea, lung, and kidney in both rats and guinea pigs showed a similar pattern as found in blood. The radioactivity in dialysed plasma from both guinea pigs and rats seemed to decay according to a two-compartment model. The non-extractable binding of [3H2]HHPA in the upper respiratory airways and conjunctiva may be of relevance for symptoms in workers with allergy, since they mainly develop symptoms and signs from the nose and eyes.

Administration, Inhalation↗
PubMed1999

Relation of TNF-related apoptosis-inducing ligand (TRAIL) receptor and FLICE-inhibitory protein expression to TRAIL-induced apoptosis of melanoma.

Past studies have shown that apoptosis mediated by TNF-related apoptosis-inducing ligand (TRAIL) is regulated by the expression of two death receptors [TRAIL receptor 1 (TRAIL-R1) and TRAIL-R2] and two decoy receptors (TRAIL-R3 and TRAIL-R4) that inhibit apoptosis. In previous studies, we have shown that TRAIL but not other members of the tumor necrosis factor family induce apoptosis in approximately two-thirds of melanoma cell lines. Here, we examined whether the expression of TRAIL-R at the mRNA and protein level in a panel of 28 melanoma cell lines and melanocytes correlated with their sensitivity to TRAIL-induced apoptosis. We report that at least three factors appear to underlie the variability in TRAIL-induced apoptosis. (a) Four of nine cell lines that were insensitive to TRAIL-induced apoptosis failed to express death receptors, and in two instances, lines were devoid of all TRAIL-Rs. Southern analysis suggested this was due to loss of the genes for the death receptors. (b) Despite the presence of mRNA for the TRAIL-R, some of the lines failed to express TRAIL-R protein on their surface. This was evident for TRAIL-R1 and more so for the TRAIL decoy receptors TRAIL-R3 and -R4. Studies on permeabilized cells revealed that the receptors were located within the cytoplasm and redistribution from the cytoplasm may represent a posttranslational control mechanism. (c) Surface expression of TRAIL-R1 and -R2 (but not TRAIL-R3 and -R4) showed an overall correlation with TRAIL-induced apoptosis. However, certain melanoma cell lines and clones were relatively resistant to TRAIL-induced apoptosis despite the absence of decoy receptors and moderate levels of TRAIL-R1 and -R2 expression. This may indicate the presence of inhibitors within the cells, but resistance to apoptosis could not be correlated with expression of the caspase inhibitor FLICE-inhibitory protein. mRNA for another TRAIL receptor, osteoprotegerin, was expressed in 22 of the melanoma lines but not on melanocytes. Its role in induction of apoptosis remains to be studied. These results appear to have important implications for future clinical studies on TRAIL.

Apoptosis↗
PubMed1999

The order of calcium and phosphate ion deposition on chemically treated titanium surfaces soaked in aqueous solution.

The mechanism of apatite deposition on chemically treated Ti surfaces still is being studied. In this study, simulated body fluid, calcium aqueous solution, phosphate aqueous solution, and accelerated calcification solution are used as media to investigate the order of calcium and phosphate ion deposition on chemically treated Ti surfaces. The results of inductively coupled plasma spectra, scanning electron microscopy, and energy dispersive X-ray analysis show that calcium deposition is the prerequisite for phosphate ion deposition.

Biocompatible Materials↗
PubMed1999

Assessment of decisions in the treatment of Helicobacter pylori-related duodenal ulcer: a cost-effectiveness study.

AIMS: Many treatment trials for Helicobacter pylori have been reported but few have evaluated treatment in terms of both cost and effectiveness. It is important to find a therapy with a high eradication rate and low cost, especially in China. The aim of the study is to assess the efficiency of therapy for duodenal ulcers, including ulcer healing, H. pylori eradication and ulcer recurrence. METHODS: Ninety-six consecutive patients with duodenal ulcers and H. pylori infection were randomly allocated into two groups: AMT group (amoxycillin + metronidazole + tagamet); OA group (omeprazole + amoxycillin). Side-effects were recorded during the treatment period. Endoscopic examinations were repeated at the 7th or 8th week to assess ulcer healing. Patients were followed up for 6 months and repeat endoscopy was performed. Ulcer healing rate, H. pylori eradication rate and ulcer recurrence rate were compared. All costs were recorded and a cost-effectiveness analysis was conducted. RESULTS: In the AMT and OA groups, the ulcer healing rate was 83.7 and 93.5%, respectively (P = 0.27). The eradication rate of H. pylori was 65.1 and 69.6%, respectively and was significantly higher in patients with an ulcer diameter < or = 1 cm compared with those with an ulcer diameter > 1 cm, irrespective of treatment group. There was no difference in recurrence rate, duration of pain or the time lost because of the disease. Moderate or severe side-effects were found in 8.9% in AMT group and 6.5% in OA group. The cost of treatment for ulcer healing, H. pylori eradication and reduction in ulcer recurrence were all lower in the AMT group than in the OA group. Sensitivity analysis supported the result that AMT was more cost effective than OA. CONCLUSIONS: The AMT therapy was more effective and less costly than the OA therapy, especially in patients with H. pylori-related duodenal ulcers < 1 cm diameter.

Adolescent↗
PubMed1999

Expression of catenins and p120cas in melanocytic nevi and cutaneous melanoma: deficient alpha-catenin expression is associated with melanoma progression.

E-cadherin mediated intercellular adhesion is regulated by a family of cytoplasmic proteins that include alpha-, beta- and gamma-catenin and p120cas. Changes in expression of E-cadherin are believed to be an early event in melanoma development. Recent studies have also drawn attention to the over-expression of beta-catenin and its possible indirect role as an oncogene in melanoma. In view of these studies, we have examined the expression of cytoplasmic proteins immunohistochemically in 13 melanocytic nevi, 34 primary cutaneous melanomas and 20 metastatic melanomas. alpha-, gamma-catenin and p120cas were heterogeneously expressed in melanocytic nevi and melanomas and were frequently absent, whereas beta-catenin expression was observed in all lesions. The pattern of expression of alpha-, beta- and gamma-catenin and p120cas was characterised by cytoplasmic and membranous immunoreactivity of varying intensity. No significant difference was found in expression of these proteins between melanocytic nevi and primary melanoma. In contrast, there was an inverse correlation between alpha-catenin expression and tumor thickness and alpha-catenin was more frequently expressed in radial compared to vertical growth phase in primary melanoma. Loss of alpha-catenin expression was observed in ten of 20 metastases compared to six of 34 primaries and the expression was more marked in primaries than in metastases. These results indicated that alterations in alpha-, beta- and gamma-catenin and p120cas expression were common in melanocytic nevi and melanomas, and that loss of alpha-catenin expression was associated with melanoma invasiveness and metastasis.

Catenins↗
PubMed1999

Preliminary study on HA coating percutaneously implanted in bone.

A comparative investigation on the possibility of hydroxyapatite (HA) coating and pure Ti column to form biological sealing with skin tissue was completed in this study. HA coating and pure Ti column were percutaneously implanted in the tibia of rabbits. Compared with titanium (Ti) implant, HA coating forms epithelial sealing with skin tissue at 6 weeks postoperatively, while the Ti implant may loosen from the implanted site and be lost. The Ti column loosing rate at this time was 50%. However, once the Ti implant becomes fixed with the bone tissue, it can form epithelial sealing with skin tissue just like the HA coating, at 8 weeks postoperatively. At 8 weeks postoperatively, the epithelial sealing is not destroyed in spite of the fact that the HA coating is biodegraded. Our results show that the HA coating can become fixed with the bone faster than the Ti, which is beneficial for epithelial sealing formation. The main role of HA coating for epithelial sealing is beneficial for sealing at the initial period after it is implanted.

Animals↗
PubMed1999

[Transformation of common wheat (Triticum aestivum L.) with herbicide-resistant EPSPs gene].

The herbicide-resistant EPSPs (5-enolpyruvylshikimate-3-phosphate synthase) gene was transformed into about 1,000 young spikes and 800 young embryos of wheat variety, Jinghua 1, with gene gun. Thirty-eight and four regenerated plants were obtained respectively screened with glyphosate. All regenerated plants were analysed by PCR and/or Southern blotting. The results indicated that EPSPs gene was integrated stably into the genome of Jinghua 1, and some of the transformants showed fertile. So herbicide-resistant EPSPs gene could be used as selective marker in the transformation of monocotyledon cereal crops, such as wheat.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗
PubMed1999

[Study of concurrent reconstruction of posterior wall of vagina with pedicled muscular flap of uterus after resection of rectum carcinoma].

OBJECTIVE: To investigate the reconstructional method of posterior wall of vagina after the resection of rectum carcinoma. METHODS: From August 1991 to March 1996, 10 patients with rectum carcinoma were adopted in this study, among them, there were 4 cases belong to B stage of Dukas, and 6 cases belong to C stage of Dukes. In operation, rectum carcinoma and posterior wall of vagina were resected, and concurrent reconstruction was finished by using pedicled muscular flap of uterus. RESULTS: The effect of operation were satisfactory except one case who was failed because of insufficient blood supply of the flap. Followed-up for 3-6 months, the posterior wall of vagina healed in 7 cases, the width of vagina was 2-3 fingers and the depth was 5-6 cm. CONCLUSION: Reconstruction of the posterior wall of vagina with pedicled muscular flap of uterus was available in clinic. For its simplicity and feasibility, it's suitable for the resection of rectum carcinoma in which the posterior wall of vagina was infiltrated.

Adult↗